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Infant Behavior & Development 31 (2008) 311–315

Brief report

Twelve-month-olds’ understanding of prioractions and final goals

James Todd ∗, Peg Hull SmithUniversity of Toledo, 2801 W. Bancroft Street, Toledo, OH 43609, United States

Received 28 July 2007; received in revised form 6 November 2007; accepted 27 December 2007

Abstract

Twelve-month-olds were habituated to trials in which a grasping action preceded the holding of an object. Infants recoveredlooking to test events when a new object was held, but only when this was preceded by prior contact with the object.© 2008 Elsevier Inc. All rights reserved.

Keywords: Goal-directed action; Grasping; Habituation; Prior action

Investigations into early social cognitive development have uncovered several important aspects of infants’ under-standing of goal-directed action. By 1 year of age, infants appear to attribute goal-directedness to grasping actions(Woodward, 1998, 1999) and encode certain forms of movement as appropriate actions for achieving a final goal-state(e.g. Gergely, Nadasdy, Csibra, & Biro, 1995; Phillips & Wellman, 2005). Much of this research has utilized visuallooking-time procedures like habituation. Here, infants typically increase looking time to test trials in which changesin goal-directed behavior are presented that differ in some meaningful way from the sequence of actions presentedduring habituation (e.g. Gergely et al., 1995; Phillips & Wellman, 2005; Woodward, 1998; Woodward & Sommerville,2000). For example, Woodward and Sommerville (2000) habituated 12-month-olds to a hand that opened the lid of oneof two containers to grasp a toy inside (both containers held a toy). With the locations of the toys inside the containersswitched at test, infants looked longer to events in which the hand attempted to open the lid of the container holdingthe toy not grasped during habituation (“new” toy/similar location) than when the hand attempted to open the containerholding the toy grasped during habituation (“old” toy/different location). Twelve-month-olds then looked longer toevents that were similar in terms of the spatio-temporal aspects of the action (i.e. reached to the same location as inhabituation), but that maintained the functional aspects of the action that were now directed at a new goal object.

By 1 year of age then, infants seem infer that a sequence of multiple actions can result in the attainment of a singlegoal. This indicates that infants expect prior actions (e.g. opening a lid) to be followed by later goals (e.g. obtaining atoy). While the mechanisms governing infants’ action understanding are hotly debated (e.g. Csibra & Gergely, 2007;Tomasello, Carpenter, Call, Behne, & Moll, 2005; Woodward, 2005), one way in which infants’ understanding of goal-directed actions may develop is through associating prior actions with the subsequent effects brought about (Elsner,2007; Hauf, Elsner, & Aschersleben, 2004; Hofer, Hauf, & Aschersleben, 2005). Over repeated pairings of actions

∗ Corresponding author at: Department of Psychology, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.Tel.: +1 305 348 7367.

E-mail address: james.todd@fiu.edu (J. Todd).

0163-6383/$ – see front matter © 2008 Elsevier Inc. All rights reserved.doi:10.1016/j.infbeh.2007.12.011

312 J. Todd, P.H. Smith / Infant Behavior & Development 31 (2008) 311–315

and their effects, infants may come to expect that certain actions will result in noticeable changes in the environment.Under this proposal the kind of action an agent produces may allow one to predict the final outcome—some actionsmay result in end-goal states while others do not.

In order to further examine infants’ understanding of goal-directed action and how certain action types come tobe associated with later action effects, 12-month-old infants were habituated to a series of events in which an actorgrasped one of two objects and was later shown holding that object. At test, the actor grasped either the same objectgrasped during habituation (familiar object) or the one ignored during habituation (novel object). In addition, the actorused either a familiar or novel grasping action when reaching for the toy. In other words, we sought to determinewhether infants would respond with increased looking to the spatio-temporal novelty of a new action (using a novelgrasping action) or to actions that maintained the functional aspects of action seen during habituation but now directedat a new object. If 12-month-olds encode the types of action presented as functionally relevant for achieving a finalgoal-state, then longer looking is expected on test trials in which the actor grasps a new object (e.g. Woodward &Sommerville, 2000). If, however, infants are sensitive to how the actor obtains a goal object, then longer lookingwould be expected when a new kind of action is presented. By manipulating the actor’s behavior in this manner,it was possible to determine the conditions under which infants would relate prior actions to final goal-directedactions.

1. Method

1.1. Participants

Forty-eight 12-month-old infants (M = 365.79 days, S.D. = 6.11; range: 355–379 days; 22 females and 26males) were tested. An additional 13 infants were tested but removed from subsequent analyses for fussiness(n = 7), experimenter error (n = 2), or failure to reach criterion (n = 4). The sample was predominately White-Non-Hispanic and from a large Midwestern city. Per parental report infants were in good physical health at the timeof testing and full-term at birth. Infants were equally distributed across the four conditions (n = 12) describedbelow.

1.2. Materials and procedure

Infants were seated on their parent’s lap inside a large observation booth containing a stage that could be concealedby curtains. Parents were instructed not to bias infants’ attention by gesturing or vocalizing. When the curtains wereopened, the actor could be seen from the torso up, seated between two objects located at equal distances from the sidesof the stage. Object A was a large brick-shaped object, while object B was a smaller brick-shaped object resting on aslender stand. Both objects were similar in size and color.

See Fig. 1 for the events depicted in the cue phase of habituation and test trials. Each individual trial (both habituationand test) contained the following general sequence of events. After the curtains opened, the actor smiled and wavedtowards the infant saying “Hi, baby! Look!”, before grasping the appropriate object and saying “Wow!” The side ofthe object grasped by the actor was counterbalanced across infants. After 7 s, the curtain closed and remained closedfor 5 s. The curtains then opened and the actor was presented always holding the object grasped prior to the curtain’sclosing. The actor then reappeared, looking towards the object and smiling until the infant looked away for more than2 s at which point the curtain was closed and the next trial began. In the familiar action/novel object condition, duringhabituation the actor grasped object A from the top, and grasped object B from the top during test trials. For the novelaction/novel object condition, the actor grasped object A in the same manner, but then grasped object B from the sideof the stand during test. Thus, these two conditions differed in terms of the spatio-temporal aspects of action, butmaintained the functional, goal-directed aspects of the action with a new object. In contrast, in the no contact/novelobject condition, the actor grasped object A from the top, but during test trials reached over as if to grasp object Bbut never made contact with the object. In this condition, both spatio-temporal and functional aspects of action weredifferent from habituation. Finally, in the novel action/familiar object condition, the actor grasped object B from thetop during habituation, but then grasped it from the side during test (i.e. the actions were spatio-temporally novel, butdirected at the same object as in habituation).

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Fig. 1. Grasping actions presented during the cue phases of habituation and test trials. During each trial the actor grasped one of the two objectsbefore being concealed by the curtain. After the curtain opened, the actor was then shown holding the object with both hands at its base. Side (leftor right) of object grasped by the actor was counterbalanced across infants.

Habituation trials ended after infants decreased their looking across three consecutive trials (criterion block) to lessthan half of their looking during the first three habituation trials (baseline block). The minimum number of habituationtrials was six, and the maximum was 14. Infants were then presented with three test trials (test block) which maintaineda similar sequence of events to that detailed above, but differed by condition. Finally, in order to assess fatigue at theend of the procedure, a brown stuffed animal was moved across the stage during a single recovery trial.

1.3. Scoring

During the procedure, infant looking times were measured by a coder who observed the live video images on atelevision screen outside infants’ view. A second coder also measured infants’ looking times from tapes of the sessionsin order to assess reliability of live coding. Both coders were naı̈ve to the hypothesis of the study. Disagreementsbetween the live and second coder (defined as more than 1 s of looking time on individual trials) were resolved byhaving the second and a third coder review and score the tapes. The second and third coders recorded looking timefrom the tapes until their level of agreement was 100% or the difference between their individual scorings was lessthan 1 s of looking time.

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Table 1Looking times during criterion and test block for each condition

Condition Criterion block Test block

Mean S.D. Mean S.D.

Familiar action/novel object 4.41 1.32 7.11 3.12Novel action/novel object 6.74 3.30 9.30 3.85No contact/novel object 6.68 3.87 6.59 2.71Novel action/familiar object 5.40 2.19 3.93 2.43

2. Results

Infants reached the habituation criterion on an average of 7.74 trials (S.D. = 2.16); the number of trials to reachcriterion did not differ across the four conditions. Mean looking during baseline block was 17.36 s (S.D. = 12.88 s),and mean looking during criterion block was 5.79 s (S.D. = 2.89 s). One infant’s mean looking time during criterionblock was greater than 2.5 interquartile ranges from the median criterion block score and this infant was removed fromsubsequent analyses.

In order to assess looking time between criterion and test blocks, a two-way, mixed-model ANOVA with trial(criterion block and test block) as the repeated measure and condition (familiar action/novel object, novel action/novelobject, no contact/novel object, and novel action/familiar object) as the between-subjects factor was conducted. Theanalysis revealed significant main effects for trial, F(1, 43) = 7.20, p = .01, η2 = .09, and for condition, F(1, 43) = 3.28,p = .03,η2 = .19. However, these main effects were qualified by a significant trial × condition interaction, F(3, 43) = 8.94,p < .001, η2 = .34, indicating that the difference in looking times between criterion and test block differed by condition.

Planned matched-sample contrasts were conducted in order to explore this interaction (see Table 1). As the actorused either a novel action or grasped a novel object during test trials, all tests were conducted as one-tailed. There wasa significant increase in looking from criterion to test block for infants in the familiar action/novel object condition,t(11) = 3.55, p = .0025, Cohen’s d = 1.91, and in the novel action/novel object condition, t(11) = 3.01, p = .006, d = 1.67.In contrast, infants in the no contact/novel object condition did not differ in terms of their looking from criterion totest block, t(10) = .127, p = n.s., and infants in the novel action/familiar object condition significantly decreased theirlooking from criterion to test block, t(11) = −3.68, p = .0005, d = 1.63. Analysis of the difference in looking fromcriterion block to recovery trial indicated that infants in every condition significantly increased their looking to therecovery stimulus and thus were not fatigued by the end of the procedure (all t’s > 4.30, all p’s < .002).

3. Discussion

Previous research has indicated that by the first birthday, infants associate prior actions with later actions byattending to the effects these actions bring about (e.g. Elsner, 2007; Woodward & Sommerville, 2000). The currentstudy investigated whether 12-month-olds would expect prior actions that were similar or different in terms of spatio-temporal novelty to be followed by later actions that depicted the obtainment of a familiar or different goal object.Infants increased looking to test events in which the actor held a new object, regardless of whether familiar or novelactions were utilized by the actor. Both familiar and novel actions differed from habituation events in that they weredirected towards a different object, but as the grasping of a new object maintained the functional aspects of that seenduring habituation, infants increased looking. In contrast, if there was no prior contact between the actor’s grasp andthe object, and thus was different in terms of spatio-temporal novelty and the functional aspects of the action, infants’looking remained constant across criterion and test block even though a new object was grasped by the actor. Thus,infants appeared to discriminate test events in which an actor held a new object only when there was prior contactbetween an action and that object. Whether they were habituated to grasping an object from the top and then testedusing the same grasp or a grasp that differed in terms of spatio-temporal aspects (i.e. from the side), infants evidentlysaw either type of grasp as a relevant way to hold an object, providing there was contact involved.

In contrast, if the actor’s holding of a familiar object at test was preceded by a new action, infants’ looking continuedto decrease across test trials. That is, if the actor’s behavior differed in terms of spatio-temporal aspects, but was identicalin its functional aspects in addition to being directed towards a familiar object, infants’ looking was significantly lower.

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It appears that, in this case, the holding of a familiar object was more relevant than any new action presented andso looking continued to decline. By 12 months of age infants appear sensitive to actions which make goals possibleregardless of differences in spatio-temporal aspects, provided the actions are relevant (i.e. maintain some functionalrelation) to achieving the goal state. Further, infants seem to understand that not making contact with an object is notfunctionally related to the later goal of obtaining that object.

When analyzing behavior, by 12 months of age infants can take into consideration both the type of action usedand the object towards which these actions are directed. Infants do not appear to simply respond to novelty on thebasis of spatio-temporal aspects alone or solely on the basis of acts that are directed towards acquiring a new object.The findings of the current study support the notion that by 12 months of age infants appear to encode a sequence ofactions as having the ultimate goal of obtaining an object (e.g. Woodward & Sommerville, 2000). Further, the findingsindicate that infants take into account the role prior actions play in determining final outcomes. Thus by 12 months ofage, infants expect certain actions to result in later goal-directed actions and are sensitive to the causal role that theseprior actions play in determining the attainment of a final goal state.

Acknowledgement

This project represents a portion of the dissertation of the first author submitted in partial fulfillment of therequirements for the PhD degree.

A fuller report of the project will be provided upon request to the first author.

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