object specificity and personla relevance in long-term visual remembering

8/18/2019 Object Specificity and Personla Relevance in Long-term Visual Remembering.

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Object specificity and personal relevance inlong-term visual remembering

Peter Walker 1, Louise Mahon1, Helen Kennedy1, and Damon Berridge2

1Department of Psychology, Lancaster University, Lancaster, UK2Department of Mathematics and Statistics, Lancaster University, Lancaster, UK

The personal relevance of an object is multi-faceted, each facet being capable of contributing to theeffects on object memory attributed to personal relevance. An object’s status as an individual object

(object specificity), rather than just a category of object, is one such facet and its impact on the long-termvisual remembering of everyday objects is assessed in two experiments. Images and drawings wereproduced under generic (e.g., ‘‘Please draw a bed’’) and personal exemplar (e.g., ‘‘Please draw yourbed’’) instructions, and participants indicated the degree to which the image on which their drawing wasbased was of a specific object or a generic object. Object specificity induced a sense of time and place fora remembered object, the most recent encounter with the object being most salient. Other aspects of personal relevance collectively facilitated the retrieval of an object’s category-irrelevant features(thereby increasing the vividness of the object image), the other objects with which it was seen, anda more general episodic sense of place. Against a broader theoretical perspective, it is proposed thatvisual episodic memory and visual knowledge are primary sources of information for specific personallyrelevant objects and generic objects, respectively.

Keywords: Visual knowledge; Visual episodic memory; Personal relevance; Object specificity; Visual imagery;

Drawing from memory.

Two recent studies highlight the significance of

people presuming ownership of an item for how

well they later retrieve information about it from

recent memory (Cunningham, Turk, Macdonald,

& Macrae, 2008; Van den Bos, Cunningham,

Conway, & Turk, 2010). Participants were shown

pictures of individual supermarket items, with

each pictured item being accompanied by a

colour cue indicating whether it should be placed

in their shopping basket or the basket of a

fictitious other person. Later recognition memory

was superior for items of which the participants

presumed ownership.The personal relevance of an item is considered

to be the important factor here, with ownership

being just one of several ways of ensuring that an

item takes on such relevance (Cunningham et al.,

2008; Van den Bos et al., 2010). Because imbuing

an item with personal relevance normally entails

changing several things about it, it follows that

there can be various ways in which such relevance

influences object memory. For example, personal

relevance normally makes an item more impor-

tant, more valuable as something that can be

traded, and more positively valenced. For any of

these reasons, such an item could be allocated

additional cognitive resources during encoding

and retention (Beggan, 1992; Belk, 1988, 1991;

Cunningham et al., 2008; Kahneman, Knetsch &

Thaler, 1991; Knetsch & Sinden, 1984). Personalrelevance might also ensure that an item is

encoded, in part, by relating it to well-established

Address correspondence to: Peter Walker, Department of Psychology, Lancaster University, Lancaster LA1 4YF, UK. E-mail:[email protected]

Memory, 2013Vol. 21, No. 2, 261 279, http://dx.doi.org/10.1080/09658211.2012.725738

# 2013 Taylor & Francis

http://dx.doi.org/10.1080/09658211.2012.725738http://dx.doi.org/10.1080/09658211.2012.725738


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schemas concerning a person’s self-concept. Theresult would be a memory representation that iselaborated to a greater extent than is the casefor items lacking personal relevance (Conway &Dewhurst, 1995; Rogers, Kuiper, & Kirker, 1977;

Symons & Johnson, 1997). Indeed, personallyrelevant items might help to shape a person’sself-concept.

Van den Bos et al. (2010) point out thatincreasing the personal relevance of an objecthighlights its status as a specific individual object,over and above its status as a member of afamiliar object category. This is because person-ally relevant objects need to be distinguishedfrom other objects of the same type. This requiresthe unique, category-irrelevant features identify-ing these specific objects (e.g., my car from

among similar cars) to be remembered. It alsoencourages us to remember a range of other factsabout the objects, such as what state they are in(e.g., whether my car is taxed and insured,whether it needs petrol) and where they can befound. Details about where personally relevantobjects have previously been encountered willinclude the relative positions and identities of other objects with which they were encountered.Furthermore, given the functional significance of the most recent of the locations in which anindividual, personally relevant item has been

encountered (because this is also likely to be itscurrent location), it becomes important to pre-serve some information about the time of eachprevious encounter with it, at least sufficient toallow the most recent location to be distinguishedfrom earlier locations. Of course, it wouldnot normally be important to retain such addi-tional information about objects lacking personalrelevance.

It follows from this that the object specificityinduced by personal relevance should encouragemore varied information to be retained about

objects and our encounters with them. This shouldnot simply make the same way of rememberingthe same information more efficient (although itcould do so, see below), it should also alter thenature of the information that is remembered. Inthis regard it is relevant to note that Van den Boset al. (2010) found that enhancing the personalrelevance of an item increased the relative in-volvement of episodic memory in the retrieval of information about the item from recent memory.Their participants reported an enhanced senseof conscious recollection (i.e., ‘‘remembering’’

rather than ‘‘knowing’’) in relation to items of

which they had presumed ownership. This accordswith the need to have available information aboutwhere individual personally relevant items can befound (i.e., the spatio-temporal context in whichthey were last encountered) and the condition

they are in. The results of Van den Bos et al.provide strong indication, therefore, that personalrelevance, and the object specificity it entails,change what we remember about objects, not justhow well we remember them.

The extent to which object specificity influ-ences object memory independently of otherfactors linked to personal relevance is unknown.At one extreme it could have no influence. At theother extreme it could explain all the effects onmemory previously attributed to personal rele-vance. The present study addresses this issue and

provides evidence for an intermediate position inwhich object specificity and personal relevanceboth make separate and distinct contributions toobject memory.

There is a relatively obvious way in whichpreserving an object’s unique features could im-prove performance in a standard recognition testof memory. In such a test recognition foils arenormally selected from the same object categoriesas the targets, making category-irrelevant featuresindispensible for distinguishing targets from foils.For example, a previously presented blue drinking

mug might be presented in a later recognition test(as a target) alongside a green drinking mug (asa foil) that wasn’t presented previously. Clearly,correctly accepting the target while rejecting thefoil requires information about the colour of theto-be-remembered mug to have been retained(with other category-irrelevant features also beinguseful). Recognition memory performance willnot normally benefit from retaining informa-tion about the features shared by all mugs (i.e.,category-defining features).

Because there is uncertainty about the level of categorisation at which targets and foils werematched by Cunningham et al. (2008) and Vanden Bos et al. (2010),1 the differential retention of

1 These two studies, as reported, leave some uncertaintyabout what might be the basis for the effects of personalrelevance they observe. Some of this uncertainty arises from

the lack of information about the stimuli. Cunningham et al.and Van den Bos et al. refer to ‘‘sets’’ of stimuli throughout.

They refer to all the stimuli they use as a ‘‘set’’ of stimuli,and then also refer to the three equivalent ‘‘sets’’ formed from

this set. Although they go on to say that items across their

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object-specific features, induced by increasingpersonal relevance, could have mediated thememory effects they observed. This would bepossible, for example, if supermarket items beingplaced in a participant’s own shopping basket

were encoded and remembered as specific objects, embracing their category-irrelevant featuresalongside their category-defining features (e.g., aspecific mobile phone, including make, model,and colour), whereas items being placed in thebasket of a fictitious other person were encodedand remembered only as categories of object,embracing only category-defining features (e.g.,

just the concept of a mobile phone). In this casethe functional significance for memory of perso-nal relevance would be mediated by the enhancedretention of category-irrelevant features induced

by object specificity.The two experiments reported here were

designed to determine if object specificity influ-ences the retrieval of object information fromlong-term memory, separately from the influenceof other factors linked to personal relevance.They were also designed to reveal if object speci-ficity influences object memory in ways consis-tent with the preceding discussion. For example,will the retrieval of information about specificobjects (regardless of their personal relevance),compared to generic objects, tend to includemore elements of the spatio-temporal context inwhich the objects were encountered (i.e., will theinformation be based on episodic visual mem-ory)? Will information about the most recentlocations in which objects were encountered beespecially prominent when information is beingretrieved about specific objects? What influ-ence, if any, will the other features linked topersonal relevance, collectively, have on objectmemory?

Participants were asked to image and draw

named objects from long-term visual memory.

They were asked in two ways, one encouragingthe retrieval of information about specific ob-

jects having personal relevance (e.g., ‘‘Pleasedraw your bed’’), the other encouraging theretrieval of information about generic objects

having no such relevance (e.g., ‘‘Please draw abed’’).2 In this way the focus of interest wason the retrieval of information about objects thathad been encoded and retained in everydaylife. The shift away from examining how tem-porary ownership in an experimental situationcan impact on temporary (i.e., relatively short-term) memory (see Cunningham et al., 2008;Van den Bos et al., 2010) served to extend thegenerality of previous work concerning theinfluence of personal relevance on object mem-ory. The shift also enhanced the ecological

validity of the study in relation to the conditionsunder which the objects had originally beenencoded and committed to memory, therebeing no attempt to control or manipulate howobjects varying in personal relevance were ori-ginally encoded. We chose to monitor aspectsof imaging and drawing partly because of abroader research agenda concerning the inter-dependencies between these two products of visual cognition.

A relatively direct approach would be to thinkof personal relevance and object specificity asdichotomous factors and create four alternativetask instructions by crossing personal relevance(relevant versus irrelevant) with object specificity(specific versus generic) in a 22 design (seeFigure 1A). For the relevant/generic and irrele-vant/specific conditions, however, this approachlacks feasibility because of the difficulty of ascertaining, in advance of the study, whichgeneric objects (i.e., object categories) havepersonal relevance for a participant, and whichspecific objects lacking personal relevance

a participant will be familiar with (see panels

three sets were matched for ‘‘item type’’ (giving ‘‘fruit’’ and

‘‘confectionery’’ as examples of such types), the matchingcould be at this or any lower level in the taxonomy of supermarket items. It is unclear, therefore, how and to what

extent foils were matched with targets in their recognition

tests. To illustrate, two examples of electrical item serving as atarget and a foil could be two different toasters or a toasterand a kettle. The information needed to distinguish target

from foil is very different in these two situations (typicalnames would suffice in the case of a toaster and kettle, but not

in the case of two toasters).

2 Although reference to ‘‘your’’ in the personally relevantinstructions implies ownership, it does not necessarily do so

in the strict legalistic sense of this term; that is, the sensethat allows someone to dispose of an item. The students whodrew their bed in the present study very likely did not own

it in a legalistic sense, but instead simply had primary claim

on its use. Either their parents or the university will haveowned it, depending whether they drew their bed in the familyhome or their bed in university accommodation. This illus-

trates the sense of ownership that is made most salient byinclusion of the term ‘‘your’’ in the personal exemplar

instructions.

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i and iv in Figure 1A).3 For the relevant/specificand irrelevant/generic conditions, however, feasi-ble instructions can be found, albeit with somelimitations regarding the degree to which theywill be able to fix the level of personal relevance

and object specificity for a named item (seepanels ii & iii in Figure 1A). For example,participants might be asked to ‘‘Please drawyour bed’’ in the relevant/specific condition, andto ‘‘Please draw a bed’’ in the irrelevant/genericcondition. Provided it can be assumed that allparticipants will have an exemplar from eachof the categories to be named, the first typeof instruction will help to ensure participants’images and drawings are of relatively specificobjects having personal relevance. Although thesecond type of instruction leaves participants free

to draw specific objects to represent the namedcategories (see Cornoldi, De Beni & Pra Baldi,1989; De Beni & Pazzaglia, 1995, for supportingevidence in relation to visual imagery), it doesmuch to encourage them to image and drawgeneric objects.4

Of course, neither type of instruction willcompletely constrain participants to image anddraw either a purely specific object or a totallygeneric object. It is known, for example, that evenwhen people intend to draw specific objects, theirdrawings contain a mix of object-specific and

generic elements, with the balance of this mixvarying across drawings (e.g., in drawing theirbed, a participant might reproduce the distinctivepatterning on the headboard, but not the distinc-tive profile of the legs, depicting these instead assimple straight lines) (see Walker et al., 2006, andBozeat et al., 2003, for examples of how object

drawings can reflect a mix of object-specific andgeneric elements). It is also known that mostvisual images of named items are initially genericin nature, and only then are elaborated to becomemore specific (Cornoldi et al., 1989; De Beni &

Pazzaglia, 1995; Kosslyn, 1981). At some inter-mediate points in time, therefore, the images willbe a mix of object-specific and generic elements.The implications of the presence of such a mix arethat object specificity is able to vary somewhatindependently of personal relevance, allowing thedistinct contributions of these two factors to beidentified.

Because the association between instructiontype and each of object specificity and personalrelevance is probabilistic in nature (see Figure1B), it was acknowledged at the outset that

statistical modelling, based on regression ana-lyses, would be needed to distinguish the influ-ence of each factor. To allow this dissociation itwas arranged for participants to indicate howspecific versus generic was the object in each of the images on which their drawings were based.Instruction type (i.e., generic instructions, such as‘‘Please draw a bed’’, versus personal exemplarinstructions, such as ‘‘Please draw your bed’’) andthis index of object specificity were then to beentered into regression analyses to see whichaspects of long-term visual remembering were

explained by object specificity, and which by allthe other factors collectively linked to personalrelevance. The steps in the argument were asfollows. It was to be determined first how much of the variation in different aspects of the imagingand drawing of named items was explained byinstruction type on its own. This variation was tobe seen as reflecting the impact of object speci-ficity and/or personal relevance. If adding objectspecificity to instruction type in the statisticalmodel then failed to add significantly to theexplanatory power of the model, the conclusion

would be that object specificity is not responsiblefor any of the effects on imagery and drawing,which instead would be attributed solely topersonal relevance. However, if adding objectspecificity explained all the effects previouslyattributed to instruction type, the conclusionwould be that the involvement of personal rele-vance is completely mediated by the object speci-ficity it induces. Alternatively, and a priori morelikely, if a significant influence of instructiontype remained after adding object specificity tothe model, the conclusion would be that personal

relevance has an independent influence on visual

3 It is assumed that an object category is less likely to have

personal relevance than a specific object. Exceptions wouldarise, for example, in relation to collectors and manufacturers

of object categories (e.g., the category of walking sticks wouldbe personally relevant to a collector of walking sticks) and to

people for whom a category of object has special importance(e.g., a disabled person who needs support from a walkingstick).

4 The tendency to access a generic representation with thistype of instruction is consistent with evidence that the names

used most frequently to refer to objects are names for objectcategories and, as such, have privileged links with visualrepresentations at an intermediate (basic) level of categorisa-

tion (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976).Thus visual representations at the basic level are evoked bythe presentation of a category label more frequently and more

quickly than visual representations at other levels of categor-

isation (Cornoldi et al., 1989; De Beni & Pazzaglia, 1995;Gardini, De Beni & Cornoldi, 2004; Hoffmann, Denis, &

Ziessler, 1983; Rosch et al., 1976).

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remembering, which remains after any contribu-tion from object specificity is accounted for.

EXPERIMENT 1: IMAGING ANDDRAWING MYCHAIR VERSUS A CHAIR

Some of the types of information about familiarobjects made salient by object specificity, and bypersonal relevance more generally (see above),were monitored to identify the distinct influencethese two factors have on memory. For example,personal relevance is expected to highlight anobject’s unique (i.e., category-irrelevant) featuresbecause, as pointed out already, it tends to bespecific individual objects that are personally

relevant. In addition it is expected that object

specificity will enhance memory for the spatio-temporal contexts in which objects were pre-viously encountered (and, conversely, there islittle need to remember such information in

relation to generic objects).In addition to monitoring the informationbeing retrieved during imaging and drawing, thetime course of imaging was monitored. Previousresearch has shown that images of specific itemstake longer to evoke than generic images, andthat images with episodic reference take longerto evoke than images lacking such reference(Cornoldi et al., 1989; De Beni & Pazzaglia,1995; Gardini et al., 2004; Kosslyn, 1981; Palladino& De Beni, 2003). The time to evoke each imagewas to be entered into multiple regression analyses

to clarify if personal relevance and/or object

personal relevance

‘Draw a bed’

‘Draw your bed’

personally relevantpersonally irrelevant

specific object

A

B

I II

IVIII

generic object

o b j e c t s p e c i f i c i t y

Figure 1. (A) The different sampling spaces associated with personal exemplar and generic instructions, with personal relevanceand object specificity represented as dichotomous variables. Shading identifies those regions of the sampling space that can be madesalient by appropriate instructions. For the unshaded regions, equivalent instructions are not available. The two elliptical sampling

spaces captured by personal exemplar instructions and generic instructions illustrate how there is the opportunity for independentvariation of object specificity and personal relevance. (B) An equivalent representation of the sampling space for both types of instruction combined, with personal relevance and object specificity both now being represented as continuous variables.



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specificity influence the fluency (speed) with

which images are evoked. It is possible, forexample, that it takes longer to access details of

previous encounters with an object (i.e., accessvisual episodic memory) than to access generic

visual information lacking episodic reference(i.e., visual knowledge). In other words, anythingthat increases the involvement of episodic mem-

ory will lengthen image evocation times. Prelimi-

nary exploration of these issues used analysis of variance. This was followed up with statistical

modelling designed to reveal the underlying pat-tern of interdependencies among the measured

aspects of imagery and drawing. As stated already,the central aim of the modelling was to assess the

extent to which object specificity and personalrelevance separately influence distinct aspects of

long-term visual memory when this is supportingthe imaging and drawing of named objects.

Method

Participants

The sample comprised 20 students and admin-

istrative staff at Lancaster University (10 males,10 females) with a mean age of 25.9 years

(range19 to 58 years, SD11.0 years). No

payment was given for their participation.

Materials

Two of the authors (LM & PW) noted the

objects that came to mind when trying to think of instances of common items that are seen and used

by most people on most days. It was from the pool

of items generated in this way (rather than froman established database) that 20 were selected as

the to-be-drawn items: cup, bed, toothbrush, sofa,

fridge, bag, phone, front door , cooker , lamp, shoe,wardrobe, wallet/purse, mirror , table, television,house, computer , shower , belt. The items wererandomly assigned to two lists of 10 items each.5

Image vividness. Participants were providedwith a black fine-tip Pilot pen and 20 A4 responsesheets. On the top side of each response sheet wasa 5-point imagery vividness scale (1very un-clear/hazy, 2 fairly unclear/hazy, 3clear but

not at all vivid, 4

quite vivid, 5

very vivid).Beneath this was an empty rectangle measuring2015 cm in which participants were to draw thenamed item.

Image specificity. On the reverse side of eachresponse sheet was a 5-point scale concerning theextent to which the completed drawing was basedon an image that was typical for the object’scategory, rather than on an image of a particularindividual object (1 purely a generic/ prototypi-cal item, 2more of a generic/prototypical itemthan a specific/particular item, 3 partly a generic/

prototypical item and partly a specific/particular

item, 4more of a specific/particular item than a generic/prototypical item, 5 purely a specific/ particular item).

Episodic reference. On the reverse side of theresponse sheet there was also a 5-point scaleconcerning the extent to which there was episodicreference in the participant’s image. This wasassessed with a single question in which episodicreference was addressed by relating it to recollec-tion of a particular past occasion. Thus partici-

pants were asked to use the scale to indicate theextent to which their image was based on aparticular past occasion when they had encoun-tered the named item (1not at all , 2not really,3 I imagined some aspects of a particular occa-

sion when I encountered the imaged item, 4 I imagined most aspects of a particular occasion

when I encountered the imaged item, 5 I imagined the whole of a particular occasion when

I encountered the imaged item).

Design

All participants were asked to image and drawall 20 items. A subset of 10 items was introducedwith generic instructions (e.g., ‘‘Please draw acup’’). The other subset, dealt with in a separateblock of trials, was introduced with personalexemplar instructions (e.g., ‘‘Please draw yourcup’’). Across all participants, each subset of items was presented under both types of instruc-tion, and the order in which each combination of item subset and instruction type was presented

was counterbalanced.

5 For both experiments reported here, the rooms in whichparticipants worked did not have any of the items to be drawn

on display. Therefore there were no models in the room onwhich participants could image and draw the named items.With regard to any relevant items that might be brought in by

participants themselves, the experimenter surreptitiously

checked that these were not in view during the study (e.g.,that their shoes remained out of sight under the table on which

they worked).

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Procedure

Participants were tested individually. It wasexplained that as soon as they had in mind adefinite image of each named item they shouldrate its vividness on the 5-point scale and then

draw the item in the rectangle below. They wereadvised that when they had completed theirsketch they should turn the page and provideratings on a further two scales. On each trialthe time to evoke an image was logged by theexperimenter. With a simple key press the ex-perimenter started an electronic counter as theynamed the item to be imaged and drawn, and thenstopped the counter the moment they saw theparticipant mark the image vividness scale.6

Results

Coding the drawings

Every participant produced a drawing for allthe named items. These were inspected by one of the authors (L.M.) and for each item a compre-hensive list was compiled of all the featuresdepicted in at least one drawing of the item. Twoindependent judges (colleagues), who did notknow the purpose of the study, or of the conditionsunder which any of the drawings had been

produced, worked through each printed list andclassified every feature as being either category-defining or category-irrelevant. A category-defining feature was described as being a featurethat is central to the item’s classification; that is,something an item needs to possess, or typicallypossesses, to qualify as belonging to the namedcategory.7 For a bag, for example, a pouch (withopening) and a handle would be category-definingfeatures. Similarly, for a bed, a base unit, legs, andheadboard would be regarded as being category-

defining (although each individual leg would notbe counted separately). The agreement between

the judges with regard to which features werecategory-defining was very high (Kappa.89).On the few occasions where there was disagree-ment, a third independent judge was consulted.The two judges then inspected the drawings and

identified which category-defining features weredepicted in each. Again there was a high level of agreement with regard to which category-definingfeatures were present and, therefore, how manysuch features were depicted in each drawing(Kappa.91). A high level of agreement alsoemerged when the two judges identified whichcategory-irrelevant features were depicted ineach drawing and, therefore, how many of thesefeatures were in a drawing (Kappa.73). Forexample, decoration of the outside of the pouchof a bag would count as a single category-

irrelevant feature, as would decoration of thehandle. Similarly, a pillow and a blanket wouldcount as two category-irrelevant features of abed. Again, the independent judge resolved thedisagreements. Figure 2 illustrates the increasedtendency to depict category-irrelevant featureswith personal exemplar instructions compared togeneric instructions. For the generic instructionsthe illustrative drawings are seen to contain twocategory-defining features in the case of the bag(i.e., the pouch and handle), and three category-defining features in the case of the bed (i.e., base,legs, and headboard). For the personal exemplarinstructions the two illustrative drawings are seento contain additional category-irrelevant features,

6 Given the experimenter knew the condition under whicheach named item was being imaged, it is acknowledged that

this is not an ideal procedure for protecting against experi-menter bias. Fortunately, the effects on image evocation timeobserved in the present study replicate the effects reported in

previous studies.7 While having four legs or a headboard are not essential

features of a bed, beds normally have four legs and a

headboard. Although they can still be categorised as a bed

without these features, to do so requires special consideration,and this might be reflected in a verbal qualification, such as

‘‘airbed’’.

generic personal exemplar

Figure 2. Typical drawings generated in response to generic

(e.g., ‘‘Please draw a bag’’) and personal exemplar (‘‘Pleasedraw your bag’’) instructions, illustrating the greater number

of category-irrelevant features depicted with the latter.



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two in the case of the bag (i.e., decoration of pouchand of handle) and three in the case of the bed(i.e., cover, motif on cover, pillow case).

Analysis of variance

Participant-based analysis of variance (ANO-VA) provided a preliminary assessment of theimpact that changing the instructions had on eachof the measures taken, including the number of category-defining and category-irrelevant fea-tures. An alpha level of .05 was selected for allstatistical tests in the present study. Each ANOVAhad Instruction Type (generic versus personalexemplar) and Serial Position (1 10) as within-participants factors, and Order (generic-personalversus personal-generic) as a between-participants

factor. Serial Position refers to the position of anitem within a subset of to-be-drawn items. Becauseitems within a subset were presented in a randomorder, that was different for each participant,Order is not of central concern here. In no casewas there a main effect of Order, or an interactionwith Instruction Type, and no further reference ismade to these.

Image specificity. Mean ratings of image speci-ficity were 1.70 (SEM 0.11) and 4.14 (SEM 0.09) for the generic and personal exemplar

instructions, respectively. The difference washighly significant, F (1, 18)312.4, pB.001, par-tial h2.95. With lower values indicating lessspecificity, the results confirm that the genericinstructions, despite allowing participants to gen-erate images and drawings of specific items, didinduce participants to generate images that weremore generic than those induced by the personalexemplar instructions.

Episodic reference. Participants’ images hadstronger episodic reference (i.e., referred to aparticular previous occasion on which they had

encountered the imaged item) following personalexemplar instructions than following generic in-structions (M 2.52, SEM 0.14, and M 1.67,SEM 0.07, respectively), F (1, 18)45.78, pB.001,partial h2.72.8

Category-defining features. The number of category-defining features depicted in a drawingdid not vary according to the type of instruction(M 2.34, SEM 0.04, and M 2.35, SEM 0.05, for generic and personal exemplar instruc-

tions, respectively), F (1, 18)B1.

Category-irrelevant features. There were fewercategory-irrelevant features depicted in drawingsproduced under generic instructions than in draw-ings produced under personal exemplar instruc-tions (M 0.22, SEM 0.03, and M 0.93, SEM 0.08, respectively), F (1, 18)116.33, pB.001, par-tial h2.87.

Time to evoke an image. The average timeto evoke an image was longer with perso-

nal exemplar instructions than with generic instruc-tions (M 6.22 s, SEM 0.41, and M 4.73 s,SEM 0.38, respectively), F (1, 18)14.45, p.001, partial h2.45.

Image vividness. Images generated in responseto personal exemplar instructions were ratedas being more vivid than images generatedin response to generic instructions (M 3.67,SEM 0.06, and M 3.12, SEM 0.08, respec-tively), F (1, 18)32.32, pB.001, partial h2.64.

Statistical modelling

These ANOVAs confirm the predictions re-garding how personal exemplar instructions,relative to generic instructions, would impact onthe measured variables. Unfortunately, however,they do not reveal the pattern of interdependen-cies among the various measures taken. Forexample, it remains unclear if the type of instruc-tion influenced the depiction of category-irrele-vant features directly, or only indirectly via itseffect on image specificity. Similarly, it remains

unclear if instruction type influenced the vivid-ness of images directly, or only indirectly via itseffect on image specificity and/or the depiction of category-irrelevant features. To gain a clearerpicture of the pattern of interdependencies

8 At first blush a mean of 2.52 seems rather low. However,the wording associated with ratings of 4 and 5 might have beenunrealistic for anything being retrieved from long-term

memory. These ratings didn’t just require some aspect(s) of a particular occasion to be imaged, they also required either

most aspects (score4) or the whole (score5) of a

particular occasion to be imaged. In which case a mean scoreof 2.52 begins to look different. It is worth noting, however,that it is the relative scores observed for different conditions

that is most pertinent, and the statistical modelling to bereported below treated the scores as such; that is, as ordered

categorical responses.

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among the various measures taken, a series of statistical models was fitted.

Preliminary explanatory variables. The contin-uous covariate Age, and the two binary variablesGender (0male, 1 female) and Order (0

personal-generic, 1 generic-personal ) were trea-ted as between-participants factors. The binaryvariable Instruction Type (0 generic, 1

personal ) was the only within-participants factor.To test whether the effect of Instruction Typevaried with Order, the first-order interactionvariable Order-By-Instruction-Type was created.Other first-order interactions could havebeen examined but were not considered in thisanalysis. The variables Age, Gender, Order, In-struction Type, and Order-By-Instruction-Typeconstituted the set of preliminary explanatoryvariables.

Ordinal categorical responses. The variable Im-age Specificity was classified as an ordinal catego-rical response repeated across 20 different imagesfor each participant. A repeated (clustered) or-dered logit or cumulative logit or proportionalodds model (Agresti & Natarajan, 2001) was usedto relate Image Specificity to the set of preliminaryexplanatory variables. The ologit command inSTATA was used with the cluster(ID) option(Rabe-Hesketh & Skrondal, 2008; STATA, 2008)

to produce robust standard errors for the para-meter estimates. The variables Episodic Referenceand Image Vividness were also regarded as re-peated ordered categorical responses. A repeatedordered logit model was used to examine theeffects of Image Specificity on Episodic Reference,while controlling for the preliminary explanatoryvariables. The same type of model also was used toexplore the impact of Image Specificity, EpisodicReference, Number of Category-Defining Fea-tures, and Number of Category-Irrelevant Fea-tures on Image Vividness, each time adjusting for

the preliminary explanatory variables.

Binary responses. The number of category-defining features and the number of category-irrelevant features were both reclassified as binaryresponses repeated over the 20 different imagesfor each participant. The number of category-defining features was recoded according towhether it wasB3 (coded as 0) or 2 (coded as1). The number of category-irrelevant features wasrecoded according to whether it wasB1 (coded as0) or 0 (coded as 1). For each binary response

separately, a repeated logit model (or repeated

binary logistic regression) (Agresti, 2002) wasfitted using the ologit command in STATA withthe cluster(ID) option (Rabe-Hesketh & Skrondal,2008). The effects of Image Specificity wereestimated in the presence of the preliminary

explanatory variables.Durations. The time interval logged by the

experimenter was considered as a duration re-peated across the 20 images. A Cox propor-tional hazards model with shared frailty (Kelly,2004) was fitted using the stcox command inSTATA with the share(ID) option (Cleves, Gould,Gutierrez, & Marchenko, 2008). This modelwas used to explore the effects of Image Specifi-city, Episodic Reference, Number of Category-Defining Features, and Number of Category-Irrelevant Features on the Time to Evoke an

Image, each time controlling for the preliminaryexplanatory variables.

Outcomes of modelling. Item specificity: Themodel containing all the preliminary explanatoryvariables was significant, Wald x 2 (5, N 400)57.45, pB.001, and explained 19% ( pseudo R 2)of the variation in Image Specificity. However,the only significant predictor of Image Specificitywas Instruction Type (Odds Ratio33.6, z5.16,

pB.001), confirming that Image Specificity washigher (i.e., imaged objects were more specific)

with personal exemplar instructions than withgeneric instructions.

Episodic reference: The model incorporatingImage Specificity and the preliminary explanatoryvariables was significant, Wald x 2 (9, N 400)89.86, pB.001, and explained 12% ( pseudo R 2)of the variation in Episodic Reference. The onlysignificant predictor of Episodic Reference wasImage Specificity. When the impact of successivelevels of Image Specificity were considered,relative to the level of least specificity, theOdds Ratios increased steadily (Odds Ratio1.8,

6.7, 7.1, 10.9, z1.86, 4.50, 4.15, 3.72, and p.06,B.001,B.001,B.001, respectively), con-firming that increasing levels of Image Specific-ity predicted higher levels of Episodic Reference.To illustrate, the highest level of Image Speci-ficity was associated with close to an eleven-foldincrease in the extent of Episodic Referencecompared to the extent associated with leastspecificity.

Category-defining features: The model incor-porating Image Specificity and the preli-minary explanatory variables was marginally

significant, Wald x 2

(9, N 400)16.13, p.06,



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accounting for less than 1% of the variation in the

Number of Category-Defining Features. None of

the variables contributed significantly to the

model.Category-irrelevant features: The model incor-

porating Image Specificity and the preliminaryexplanatory variables was highly significant, Wald

x 2 (9, N 400)595.75, pB.001, explaining 17%

of the variation in the Number of Category-

Irrelevant Features. Only Instruction Type con-

tributed significantly to the model (Odds

Ratio6.97, z8.01, pB.001), confirming that

drawings produced under personal exemplar in-

structions were almost seven times more likely to

depict at least one category-irrelevant feature

than were drawings produced under generic

instructions.Time to evoke an image: Two variables from

the set of preliminary explanatory variables were

the only variables to impact significantly on

Image Evocation Time. Adding other variables

to the model failed to increase its explanatory

power even though, when considered alone, some

appeared to have a significant impact on Image

Evocation Time (e.g., extent of episodic reference

and number of category-irrelevant features). The

model incorporating just the preliminary ex-

planatory variables was significant, Wald x 2

(5, N 400)56.78, pB.001. Instruction Type(Hazard Ratio0.4; z6.07; pB.001) and

Age (Hazard Ratio0.97; z2.54; p.011)

both impacted significantly on Image Evocation

Time, with images taking longer to evoke in

response to personal exemplar instructions than

in response to generic instructions, and as the age

of the participants increased.Image vividness: Other than Instruction Type,

only the number of Category Irrelevant Features

impacted significantly on Image Vividness. The

final model that included this variable along with

the preliminary explanatory variables was signifi-

cant, Wald x2(6, N 400)57.09, pB.001, ex-plaining 6% ( pseudo R 2) of the variation in Image

Vividness. More vivid images were induced

by personal exemplar instructions than by gen-

eric instructions (Odds Ratio2.50, z3.10,

p.002). Images containing at least one cate-

gory-irrelevant feature also were more vivid than

images with no such features (Odds Ratio1.46,

z1.99, p.046).Figure 3 summarises the pattern of interdepen-

dencies revealed by the regression analyses.

Discussion

Personal exemplar instructions, compared togeneric instructions, made it more likely thatspecific individual objects, rather than genericobjects, would be imaged. Mediated by thisincrease in the specificity of the imaged objects,personal exemplar instructions also introduced an

element of episodic reference, with participantsbeing more likely to confirm that each of theirimages related to a particular occasion on whichthe imaged object had been encountered. AsFigure 3 shows, instruction type also impacteddirectly on other aspects of imaging and drawing.Independent of their impact on image specificity,personal exemplar instructions increased thevividness of the images. They did this bothdirectly and indirectly by increasing the presenceof category-irrelevant features. It would appear,therefore, that the presence of category-irrelevant

features, rather than of episodic reference, en-hances image vividness. As expected, neitherobject specificity nor personal relevance, as dis-tinct aspects of the contrast in type of instruction,influenced the number of category-defining fea-tures depicted in a drawing.

It would appear that personal relevance andobject specificity can each influence the typeof object information that is remembered. Thepersonal relevance of an object directly enhancesmemory for its unique (category-irrelevant)features. It can do so without reference to

any episodic information relating to previous

instruction type

specificity of image

vividness

age

episodic reference to a previous occasion

number of cat.defining features

image evocation time

number of cat.irrelevant features

Figure 3. The interdependencies among different measured

aspects of imaging and drawing revealed through regressionanalyses of the consequences of adopting personal exemplar

instructions rather than generic instructions in Experiment 1.

Continuous lines depict influences attributed to imaged objectspecificity, whereas dashed lines depict influences attributed toother factors collectively identified as personal relevance.

270 WALKER ET AL.


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encounters with the object. On the other hand,the more specific (less generic) the object infor-mation being retrieved, the more relevant are thedetails (e.g., the spatio-temporal coordinates) of previous encounters with this named object, and

the more likely are these details to be retrieved.Conversely, of course, episodic information relat-ing to encounters with specific objects is notretrieved as part of the generic informationabout objects (i.e., information pertinent to theircategories).

Finally, images can take longer to evoke inresponse to personal exemplar instructions com-pared to generic instructions. This is consistentwith previous research showing that images of specific items take longer to evoke than images of generic items, and that images with episodic

reference take longer to evoke than imageslacking such reference (Cornoldi et al., 1989; DeBeni & Pazzaglia, 1995; Gardini et al., 2004;Kosslyn, 1981; Palladino & De Beni, 2003).Because in the present study the time to evokean image was directly dependent on instructiontype, without any mediation from object specifi-city, it would appear that personal relevance wasprimarily responsible for the extra time neededto generate an image with personal exemplarinstructions.

EXPERIMENT 2: ELABORATING THENATURE AND DETERMINANTS OF

EPISODIC REFERENCE

In Experiment 1 the effect of instruction type onepisodic reference was mediated entirely by thespecificity of the imaged object: The more genericthe imaged object, the less reference there was toepisodic information. The absence of any linkbetween personal relevance and episodic refer-

ence is a little surprising given the importance of keeping track of where personally relevant itemsare to be found and what state they are in.

Episodic memories preserve information aboutwhen and where individual items have previouslybeen encountered, with where including referenceto other objects in the scene at the time. InExperiment 1 the involvement of episodic mem-ory was indexed by a single question concerningthe extent to which an image of a named itemrelated to a particular occasion on which the itemhad been encountered. Unfortunately the term

occasion leaves some uncertainty regarding which

aspect of episodic reference is most salient (i.e.,the extent to which an occasion is defined by thewhen and/or the where).

Experiment 2 was designed to provide addi-tional information regarding the separate influ-

ence of object specificity and personal relevanceon the when and where of episodic visual memory.It was predicted that some aspects of episodicreference would be linked directly to each of these factors. Specifically, given the importance of knowing where personally relevant objects can befound, it was expected that personal relevancewould be linked to the retrieval of informationabout the location of the previous encounter onwhich the image of an object is based.

Method

The method was essentially the same as thatadopted in Experiment 1. However, the focus of interest was limited to instruction type and imagespecificity, which were the only significant pre-dictors of episodic reference in Experiment 1.

Participants

The sample comprised 20 students and admin-istrative staff at Lancaster University (5 males, 15females) with a mean age of 21.8 years (SD8.0years). No payment was given for their participa-tion, although the students received course credit.

Materials

There was just one change to the list of 20 to-be-drawn items. This involved replacing belt , forwhich relatively few category-irrelevant featureswere offered, with watch.

Image specificity. On the reverse side of eachresponse sheet was a slightly modified 5-pointscale designed to assess the extent to which thecompleted drawing was based on an image thatwas typical for the object’s category, rather thanon an image of a particular individual object(1completely typical, not at all a particular individual object , 2mostly typical, slightly a

particular individual object , 3an equal mix of a typical and of a particular individual object ,4 slightly typical, mostly a particular individual object , 5not at all typical, completely a particu-

lar individual object ).



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In addition there were three new questions tobe answered concerning the when and where of any previous encounter that provided the mem-ory representation on which the image was based.

Episodic reference to a specific time and

recency. The first of these new questions requiredparticipants to indicate the extent to which theirimage of the named object was linked to a spe-cific time when the object was encountered(1clearly from a specific time, 2 somewhat

from a specific time, 3not at all from a specifictime). The second new question required partici-pants to provide an estimate of the recency of their encounter with the object. Specifically, theywere asked to indicate how many times they hadseen the named object since the specific time(encounter) from which their image came. Parti-cipants were asked to provide such an estimate inthose cases where they had indicated their imageof the named item was either clearly from a

specific time or somewhat from a specific time.

Episodic reference to a specific place. The thirdnew question required participants to indicatethe extent to which their image of the namedobject was linked to a specific place in whichthe object was encountered (1clearly from a

specific place, 2 somewhat from a specific place,3not at all from a specific place).

Episodic reference: Inclusion of additional

objects in the image. The where context for animage was also assessed with a question thatasked participants to name any other objects intheir image. Any such other objects were to beregarded as providing the scenic context forthe encounter (i.e., the objects were alongsidethe named object in the particular encounter onwhich their image was based).


objects in the drawing. Finally, at the conclusion

of the experiment the experimenter and an in-dependent judge identified any further additionalobjects that were depicted in the drawing of eachnamed object.9

Apart from these changes, the method was thesame as for Experiment 1.

Results

Coding the drawings

Every participant produced a drawing of all thenamed items. These were inspected by one of theauthors (H.K.) and an independent judge (i.e., acolleague who did not know the purpose of thestudy, or of the conditions under which any of thedrawings had been produced), and for each item anote was made of any objects, other than thenamed object, that were depicted in the drawing.Subsequently, where there was lack of agreement,this was resolved through discussion. Figure 4

shows two typical drawings produced underpersonal exemplar instructions in which addi-tional objects were included.

Analysis of variance

Participant-based ANOVA provided a preli-minary exploration of the impact of instruction

Figure 4. Typical drawings generated in response to personalexemplar instructions in Experiment 2, illustrating the inclu-

sion of other objects from the encounter on which the drawing

of the named object is based. The drawings were produced inresponse to the instructions ‘‘Please draw your TV’’ and

‘‘Please draw your bed’’.

9 Although the theoretical significance of the presence of other objects in participants’ images and drawings was not

appreciated in advance of Experiment 1, so their presence wasneither indexed nor analysed, it was noticed that some of thedrawings incorporated such objects. Rather than conduct a

post hoc analysis to examine their presence as an independent

variable, it was decided to derive theoretically motivatedexpectations relating to their presence in preparation for

Experiment 2.

272 WALKER ET AL.


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type on each of the measures taken. Each

ANOVA had Instruction Type and Serial Posi-

tion as within-participants factors. No between-

participants factors were included.

Image specificity. Mean ratings of imagespecificity were 2.24 (SEM 0.14) and 3.89

(SEM 0.19) for the generic and personal ex-

emplar instructions, respectively. The difference

was highly significant, F (1, 19)101.3, pB.001,

partial h2.84. With lower values indicating less

specificity, the results confirm that the generic

instructions induced participants to generate

images that were more generic than those induced

by the personal exemplar instructions.

Episodic reference to a specific time. Partici-

pants’ images were associated with a strongersense of being linked to a specific time following

personal exemplar instructions than following

generic instructions (M 2.02, SEM 0.13, and

M 2.53, SEM 0.07, respectively), F (1, 19)

14.54, p.001, partial h2.43. Figure 5 also

confirms the presence of a recency effect linked

to participants’ claims that their images were

clearly from a specific time. When participants

made this claim their image was most likely to be

based on their most recent encounter with the

named item, a trend that was less evident whenthey claimed their image was only somewhat from

a specific time.

Episodic reference to a specific place. Partici-pants’ images were associated with a strongersense of being linked to a specific place followingpersonal exemplar instructions than followinggeneric instructions (M 1.43, SEM 0.07, and

M

2.30, SEM

0.07, respectively), F (1, 19)

97.76, pB.001, partial h2.84.


objects in the image. Participants’ images weremore likely to incorporate an additional objectfollowing personal exemplar instructions than fol-lowing generic instructions (M 1.31, SEM 0.15, and M 0.50, SEM 0.08, respectively),F (1, 19)55.43, pB.001, partial h2.75.


objects in the drawing. In general, fewer addi-

tional objects were included in the drawingsthan in the images, suggesting either someediting or some loss of information as the imagewas translated into a drawing. Neverthelessparticipants’ drawings, like their images, weremore likely to incorporate an additional objectfollowing personal exemplar instructions thanfollowing generic instructions (M 0.93, SEM 0.10, and M 0.28, SEM 0.05, respectively),F (1, 19)61.05, pB.001, partial h2.76.

Statistical modellingPreliminary explanatory variables. The contin-

uous covariate Age, and the two binary vari-ables Gender (0male, 1 female) and Order(0 personal-generic, 1 generic-personal ) wereagain treated as between-participants factors. Thebinary variable Instruction Type (0 generic,1 personal ) was the only within-participantsfactor. First-order interactions were not consid-ered in this analysis. The variables Age, Gender,Order, and Instruction Type constituted the set of preliminary explanatory variables.

Ordinal categorical responses. The variableImage Specificity was again classified as anordinal categorical response repeated across 20different images for each participant (cf. Experi-ment 1). A repeated (clustered) ordered logit orcumulative logit or proportional odds model wasused to relate Image Specificity to the set of preliminary explanatory variables. The variablesSpecific Time and Specific Place were alsoregarded as repeated ordered categorical re-sponses. A repeated (clustered) ordered logit

model was used to examine the effects of Image

60

50

40

f r e q u e n c y

30

20

0

10

21 >=430

number of encounters with the imaged object

since the encounter on which the image is based

‘clearly from a specific time’

‘somewhat from a specific time’

Figure 5. The recency effect that emerged when participantsin Experiment 2 confirmed that their drawings were based onencounters with a strong sense of being linked to a specific

time. Note the more pronounced recency effect when theimage was ‘‘clearly from a specific time’’ as opposed to

‘‘somewhat from a specific time’’.



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Specificity on these two variables, while control-ling for the preliminary explanatory variables.

Count data. The number of other objectsincluded in an image of a named item (i.e.,Additional Objects) was treated as a count

variable and referred to the Poisson distributionfor analysis. The poisson command in STATA wasused to relate this variable to the preliminaryvariables and Image Specificity, with the clus-ter(ID) option again being used to produce robuststandard errors for the parameter estimates.

Outcomes of modelling. Image specificity:The model containing all the preliminary ex-planatory variables was significant, Wald x 2(5,N 400)105.94, pB.001, and explained 11%( pseudo R 2) of the variation in Image Specificity.

However, the only significant predictor of Image Specificity was Instruction Type (OddsRatio9.33, z8.00, pB.001), confirming thatImage Specificity was higher (i.e., imaged objectswere more specific) with personal exemplarinstructions than with generic instructions.

Episodic reference to a specific time: Themodel incorporating Image Specificity and thepreliminary explanatory variables was significant,Wald x 2(9, N 400)39.74, pB.001, and ex-plained 14% ( pseudo R 2) of the variation inSpecific Time. The only significant predictor of

Specific Time was Image Specificity. When theimpact of successive levels of Image Specificitywere considered then, relative to the level of leastspecificity, the Odds Ratios decreased steadily(Odds Ratio0.22, 0.09, 0.07, 0.08, z3.37,4.59, 3.92, 3.90, all pB.001), confirmingthat increasing levels of Image Specificity pre-dicted an increasing sense that an image waslinked to a specific time. To illustrate, the highestlevel of Image Specificity was associated withclose to a 13-fold increase in the strength of thesense that a specific time was present, compared

to the strength associated with least specificity.Episodic reference to a specific place: The

model incorporating Image Specificity and thepreliminary explanatory variables was significant,Wald x 2(9, N 400)131.79, pB.001, and ex-plained 23% ( pseudo R 2) of the variation inSpecific Place. Instruction Type and Image Spe-cificity were both significant predictors of SpecificPlace. The Odds Ratio for Instruction Type was0.27 (z4.23, pB.001), confirming that perso-nal exemplar instructions, relative to genericinstructions, induced a greater sense that the

image was linked to a specific place. When the

impact of successive levels of Image Specificitywere considered, relative to the level of leastspecificity, the Odds Ratios decreased steadily(Odds Ratio0.20, 0.11, 0.05, 0.05, z3.94,4.78, 4.44, 4.85, all pB.001), confirming

that increasing levels of Image Specificity pre-dicted an increased sense that an image waslinked to a specific place. The highest level of Image Specificity was associated with a 20-foldincrease in the strength of the sense that a specificplace was present, compared to the extent asso-ciated with least specificity.


objects in the image. The model incorporatingImage Specificity and the preliminary explana-tory variables was significant, Wald x 2(9,

N

400)

353.91, pB

.001. Instruction Type wasthe only significant predictor of Additional Ob- jects, Incidence-Rate Ratio (IRR)2.37, z5.82, pB.001, confirming that it had a direct influenceon the retrieval of additional objects, irrespectiveof how generic or specific was the information onwhich the image was based. Successive levels of Image Specificity were not associated with anincreasingly significant impact on the number of additional objects. For only one of the foursuccessive levels of change in Image Specificitywas there a significant impact on the number of

additional objects ( IRR

1.44, 1.63, 1.51, 1.70,z1.95, 2.05, 1.46, 1.74, p.052, .04, .15, .08).Figure 6 summarises the pattern of interdepen-

dencies revealed by the regression analyses.

Discussion

Experiment 2 reveals the different ways in whichpersonal relevance and object specificity enhanceepisodic reference. All three aspects of episodicreference were enhanced when personal exem-

plar instructions, rather than generic instructions,were adopted, and statistical modelling confirmedthe separate contributions from object specificityand personal relevance.

With regard to episodic reference to a specifictime, the impact of instruction type was mediatedentirely through its influence on image specificity.Images of specific individual objects, compared togeneric images, were accompanied by a strongersense of a specific time at which an imaged objecthad previously been encountered. Furthermore,as expected on the grounds that the most recent

of previous encounters is especially salient

274 WALKER ET AL.


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because it is most likely to be an object’s currentlocation, there was a strong recency effect asso-ciated with images of specific objects: It was themost recent encounter with a specific object thattended to provide the basis for an image of theobject (see Figure 5).

Instruction type had both a direct effect on the

sense that an image was linked to a specific place,and an indirect effect via image specificity. Itappears, therefore, that both personal relevanceand object specificity increase the sense that theinformation being retrieved from long-term mem-ory relates to a particular spatial location in whichthe object had been encountered.

Finally, adopting personal exemplar instruc-tions, rather than generic instructions, induced theinclusion of other objects in the images anddrawings of the named items. Because this wasindependent of object specificity, it is attributed

to personal relevance. Looking across both ex-periments, the functional significance of personalrelevance appears to be the same with regard tothe inclusion of other objects (i.e., objects provid-ing the scene for a previous encounter) and withregard to the inclusion of an object’s category-irrelevant features (see Experiment 1). In bothcases the enhancements occur without referenceto the spatio-temporal aspects of previous en-counters (i.e., an episodic sense of time andplace).

Finally, given that it was only episodic re-

ference to a specific time that behaved in the

same way as reference to an occasion in Experi-ment 1 (i.e., both were driven entirely by imagespecificity, and not at all by instruction typedirectly), it would appear that to make referenceto an occasion can be, in effect, to make reference

just to the sense of time linked to an encounter.

GENERAL DISCUSSION

There are many ways in which an object canbecome personally relevant to an individual, andpresuming ownership of the object is just one of these ways (Cunningham et al., 2008; Van den Boset al., 2010). However it is achieved, enhancingthe personal relevance of an item brings withit several other changes, any of which could

contribute to the impact personal relevance hason object memory. For example, it is normallyspecific individual objects that become personallyrelevant (rather than categories of object) (seeVan den Bos et al., 2010), and this enhancedobject specificity is very likely to impact onmemory. Employing a task situation in whichparticipants were asked to retrieve visual infor-mation about familiar objects from long-termmemory, the present study sought to confirm theseparate contributions to object memory of objectspecificity and personal relevance.

It is argued that object specificity and personalrelevance should influence what is rememberedabout our experiences of objects, and not just howwell the same information is remembered. Forexample, the category-irrelevant features identi-fying specific, personally relevant objects need tobe remembered, along with a range of other facts,such as what state the objects are in and wherethey can be found. Details regarding the lattershould include the relative positions and identitiesof other objects involved in previous encounters,along with information about the time of each

previous encounter with a particular object, atleast sufficient to allow its most recent location tobe distinguished from earlier locations (which ismost likely to be its current location). On thisbasis memory for specific, personally relevantobjects, and for more specific objects regardlessof personal relevance, should include more ele-ments of the spatio-temporal context in which theobjects were encountered. The presumed increas-ing involvement of visual episodic memory inremembering specific, personally relevant objectsis entirely consistent with Van den Bos et al.’s

(2010) observation that enhancing personal

instruction type

specificity of

image

image referred to

specific place

image referred to

specific time (with a strong element of

recency)

number of

other objects in image

Figure 6. The interdependencies among different aspects of imaging revealed through regression analyses of the conse-quences of adopting personal exemplar instructions rather

than generic instructions in Experiment 2. Continuous linesdepict influences attributed to imaged object specificity,whereas dashed lines depict influences attributed to personal

relevance.



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relevance, through ownership, increases the like-lihood that participants will have a consciousrecollection of having previously seen an object(i.e., they will ‘‘remember’’ the object rather than

just ‘‘know’’ they have seen it before). More

generally, this observation provides strong indica-tion that personal relevance, and the objectspecificity it entails, changes what we rememberabout objects, rather than just how well weremember them.

To identify the separate and distinctive con-tributions of object specificity and personal re-levance to object memory, the two experimentsreported here employed a task in which partici-pants imaged and drew familiar named objectsfrom long-term memory. They did this in responseto two different types of instruction, one type

encouraging them to image and draw genericobjects (e.g., ‘‘Please draw a bed’’), and anothertype encouraging them to image and draw specificobjects of personal relevance to them (e.g.,‘‘Please draw your bed’’). By asking participantsto indicate how specific versus generic the objectin each of their images was, statistical modelling(based on multiple regression) successfully dis-sociated the influence each of the two factors hadon various aspects of imaging and drawing fromlong-term visual memory.

By contrasting the images and drawings gen-

erated in response to generic and personalexemplar instructions, it was confirmed that theobject specificity that is induced by enhancedpersonal relevance has its own impact on objectmemory, separately from the impact that perso-nal relevance otherwise has. These two factorsimpacted in different ways on the types of information about named objects that are re-trieved from long-term visual memory. Personalrelevance induced the retrieval of a namedobject’s category-irrelevant features (i.e., theunique features identifying that specific object)

and the retrieval of the other objects with whichit had previously been encountered (i.e., objectsproviding the context for a particular encounter).By increasing the presence of category-irrelevantfeatures of the object, personal relevance alsoenhanced the vividness of the image of an object.On the other hand, object specificity induced agreater sense that the information being retrievedis linked to a specific time in the past, with themost recent encounter with an object being themost salient. Personal relevance and objectspecificity both enhanced the sense that the

information being retrieved is linked to a parti-

cular place. The corollary of all of this was thatretrieving generic information tended not toinclude information about the timing of anyrelevant previous encounters or of episodicfeatures more generally.

These are novel findings, which extend pre-vious work by revealing the contributions toobject memory of one distinct factor thought toco-vary with other factors as an aspect of personalrelevance. The present study also demonstratesthe appropriateness and power of one approachto statistical modelling that could be usefullyapplied to isolate other factors contributing topersonal relevance. Furthermore, by shifting thefocus away from examining how temporary own-ership in an experimental situation can impact ontemporary (i.e., relatively short-term) memory

(see Cunningham et al., 2008; Van den Boset al., 2010), and towards the long-term conse-quences of personal relevance for rememberingobjects encoded in everyday life, the presentstudy extends the generality and ecological valid-ity of previous work. Finally the present studyincorporates some potentially fruitful links withother work, from which a broader theoreticalperspective can be brought to bear.

It is proposed here that generic visual informa-tion lacking personal relevance is retrieved fromvisual knowledge, whereas visual information

about specific objects having personal relevanceis retrieved from visual episodic memory (whatKosslyn, 1994, refers to as the category patternactivation and exemplar pattern activation systemsrespectively).10 Visual knowledge is generallyregarded as incorporating information specifyingthe prototypical visual features of item categoriesat varying levels of abstraction (i.e., the visualknowledge base explored by Rosch et al., 1976).It is to this type of visual representation thatother category information is linked, includingthe name of the category. Visual episodic memoryis thought to preserve records of encounters withparticular objects, allowing the encounters to bere-experienced. Thus episodic memories preserveinformation identifying the particular objectencountered (i.e., including its category-irrelevantfeatures) and the context in which it was

10 There is neuropsychological evidence that visual knowl-edge and visual episodic memory are distinct cognitive

resources. For example, depending which regions of the brain

are damaged through injury, either one of these sourcesof information can be selectively degraded (Kapur, 1999;

Tulving, 2002; Wheeler & McMillan, 2001).

276 WALKER ET AL.


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encountered; that is, the when and where of theencounter, with the latter including the otherobjects providing a context for the encounter.11

The contributions of visual knowledge andvisual episodic memory are not thought to be

mutually exclusive, but instead are thought to becapable of contributing simultaneously to thesame visual image. This is implied by the viewthat visual images can have a mix of object-specific and generic elements, which in turn isconfirmed by previous observations that imagesof named items are initially generic in nature andonly then are elaborated to become more specific(Cornoldi et al., 1989; De Beni & Pazzaglia, 1995;Kosslyn, 1981) and more episodic (Gardini et al.,2004; Palladino & De Beni, 2003). It would seem,therefore, that at some intermediate point in their

generation images will reflect the combinedinfluence of visual knowledge and visual episodicmemory. This account also explains why specificimages were observed to take longer to evokethan generic images in Experiment 1.

Episodic memory seems to be especially vul-nerable to the effects of increasing age (see Light,1991, for a review). If this means episodicmemory becomes increasingly difficult to use,then we have an explanation for the effect of age on image evocation times in Experiment 1.When explicitly instructed to generate an image

of a specific object that is personally relevant, anyparticipants finding this difficult to do will needextra time to do so. Although Palladino and DeBeni (2003) observed specific images to be lessfrequently generated with age, relative to genericimages, the present findings suggest it might beimportant to examine further whether it is speci-ficity that is the key feature. The effects of age onimage evocation time were independent of objectspecificity and could be reflecting difficulties inaccessing visual episodic memory generally.

People suffering either from major depressive

disorder (see Williams & Scott, 1988, and Wil-liams et al., 2007, for a review), or from post-traumatic stress disorder (Schonfeld & Ehlers,2006), are two additional groups who find itdifficult to access memories of specific episodesin their life that occurred at a particular time andplace on a particular day. Instead they retrievegeneric information about a category of event.For example, in response to the cue word party, or

an equivalent picture, they might respond bysaying ‘‘I always enjoy a good party’’ but not bysaying ‘‘I enjoyed Jane’s party last Friday’’ (cf.Williams et al., 2007). In light of the evidencefrom the present study, and the theoretical frame-

work within which it is placed, it is predicted thatthe visual images and drawings of these sameclient groups will show much less sensitivity to therequirements associated with personal exemplarinstructions compared to generic instructions.That is, they will tend to continue to rely onvisual knowledge and the generic information thismakes available. If this is confirmed, then thefeatures of images and drawings that signal thedifferential involvement of visual knowledge andvisual episodic memory could provide usefulconfirmation as to when emotional disturbance

is impacting on a person’s ability to accessinformation preserved in their episodic memory.This would be particularly useful, of course, forclient groups who are unable or unwilling tocommunicate verbally with the levels of fluencyrequired when depression is being assessed inmore conventional ways.

Finally, the present results resonate with thosefrom other studies in which drawing has been usedto identify the circumstances under which genericand object-specific episodic information are pre-ferentially retrieved from visual memory (Walker,

Blake, & Bremner, 2008; Walker, Bremner, Smart,Pitt, & Apsey, 2008; Walker, Kennedy, & Berridge,2011). In these studies, in which participants hadto draw a small number of objects from re-cent memory, Walker and his colleagues gavethemselves the opportunity to manipulate theavailability of generic visual information (i.e.,information about object categories) by usingobjects that were novel. The creation and utilisa-tion of generic information was then controlled byarranging for each object either to be named atencoding with a novel count noun (‘‘This is a dax’’)

or to not be so named (‘‘This is an object’’), theassumption being that only in the former casewould generic information about the objects beestablished (see Walker, Bremner, et al., 2008, for areview of evidence justifying this assumption).When the objects were named at encoding, andno constraints were imposed on how they should bedrawn, participants revealed a bias towards draw-ing them in a way that reflected their genericaspects, rather than in a way that reflectedhow they had been experienced. Specifically, theobjects were drawn in unseen prototypical orienta-

tions, rather than in the orientations in which they

11 The context in which an object was encountered will alsoinclude how it was encountered (e.g., its orientation from the

viewpoint from which it was seen).



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had been seen. However, when the objects were

not named at presentation, so that generic re-

presentations were not available, they tended to be

drawn in the orientations in which they had beenseen.12

Walker and his colleagues propose thatalthough information about how individual ob-

jects had previously been experienced is pre-served in long-term visual memory, people

prefer to make use of generic information about

the objects. In other words, the bias to retrievegeneric information about objects from long-term

visual memory is a matter of choice that reflects

the relative accessibility, rather than availability,

of generic and episodic representations. Evidence

supporting this proposal was obtained from a

condition in which participants were asked to

draw named objects specifically in the orienta-

tions in which they had been seen. Despite the

bias towards prototypical orientations that would

normally be in evidence, participants were able to

draw the objects in the orientations in which they

had seen them (Walker et al., 2011).To summarise, therefore, in the context of

much longer-term memory than was examined

by Walker and his colleagues, the results of the

present study support their proposal that generic

and object-specific episodic memory representa-

tions can co-exist in long-term memory, and that adifference in their accessibility, rather than their

availability, normally induces a bias towards

relying on the former whenever this is acceptable.

The results of the present study confirm that

other types of information linked to visual

episodic memory also will be retrieved when

circumstances discourage reliance on generic

information. Thus, in addition to the orientation

in which an object was previously encountered,

discouraging reliance on generic representations

will induce the retrieval of information providing

a sense of time and place, information regarding

an object’s unique features, and information

about other objects encountered at the same time.

Manuscript received 5 December 2011

Manuscript accepted 28 August 2012First published online 21 September 2012

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