Motivationally significant stimuli show visual prior entry: Evidence for

attentional capture

West, G., Anderson, A., & Pratt, J. (2009). Journal of Experimental Psychology: Human Perception and Performance, 35(4), 1032-1042.

Outline

• Why did this study?

-- Other tasks’ restrictions

• Visual prior entry

• Temporal order judgments(TOJ)

• Experiment 1 to 6

• Conclusion

Why did this study?

(1) No study to date has specifically measured

how attention is initially deployed toward

these stimuli.

(2) Past studies provide little information about

the exact extent to which these stimuli are

initially prioritized by the visual– attentional

system because initial attentional

deployment was not directly measured.

Other tasks’ restrictions

Visual search and change detection:

(1) Redistribution of attention focus to multiple

spatial location.

(2) Attention is likely reallocated several times

before a response is made.

(3) These paradigms may not provide an

adequate measure of the very earliest

deployment of attention.

(Posner, Walker, Friedrich, & Rafal, 1984)

• Their studies assess a global attentional measure created by gauging a combination of different attentional processes. [(1),(2),(3)]

(1) Attentional disengagement

(2) Attentional shifting

(3) Attentional reengagement

However, they do not measure degrees of

initial attentional deployment.

Visual Prior Entry

• Is assessed by temporal order judgments (TOJs)

Temporal order judgments(TOJ)

• TOJ is a sensitive measure of initial attentional deployment.

• TOJ provides a direct and accurate measure of attentional capture.

• TOJ tasks use cues to shift spatial attention to a particular location before the onset of two target items separated by some variable interval.

How to get TOJ response function

• Participants report which target item had the first onset at different stimulus onset asynchrony (SOA) intervals, producing a TOJ response function.

TOJ response function

Perceived stimulus simultaneity (PSS)

Perceived stimulus simultaneity (PSS)

• The interval needed for the participants to perceive both target items as arriving simultaneously.

PSS

• PSS shows how much time the unattended stimulus must occur before the attended stimulus, due to prior entry, for them to be perceived as occurring simultaneously.

Experiment 1-6

Experiment 1

• Hypothesis:

A face, a stimulus of social and biological relevance, captures attention by contrasting a face with an inverted face stimulus.

Procedure

Result

The dashed vertical line to the right of the arrows represents the actual perceived stimulusSimultaneity calculated from the TOJ function.

Result

• The effect of prior entry was assessed by calculating each participant’s individual PSS, indicating the interval needed for the participant to perceive both target items as arriving simultaneously.

(see previous graph: 50%’s location)

• The average PSS was 5.88 ms, which was significantly different from zero, t(15) 2.31, p <0.038, indicating a prior entry effect for the face.

• The inverted face would need to be displayed almost 6 ms before the upright face for both stimuli to be perceived as arriving at the same time.

Experiment 2

• Link with Exp. 1:

The researcher wants to know whether emotional faces also have visual prior effect, compared with neutral faces.

• Hypothesis:

Emotional displays have privileged status and thus have greater attention capturing properties than faces with neutral expressions.

Procedure

• The procedure is the same as Exp.1. It only replaced the neutral schematic faces with

Result

Result

• The average PSS was found to be 7.85 ms,

• which significantly differed from zero, t(13) 2.59, p< 0.025, indicating a prior entry effect for the threatening face.

• A face with a neutral configuration would have to be presented almost 8 ms before a face with a threatening configuration for both items to be subjectively perceived as arriving simultaneously, thus demonstrating that facial displays of threat capture attention.

Experiment 3

• Prior studies have shown that facial inversion disrupts the processing of emotional content (e.g, McKelvie, 1995; Phelps et al., 2006; Pourtois et al., 2005).

Experiment 3

• They want to know that visual prior entry effects for the angry face were driven by

which one, (1) or (2)?

(1) holistic processing

(2) low-level featural differences

Experiment 3

• Link with Exp. 2:

Compared with Exp.2, Ex.3 controls face’s features.

Procedure

• The procedure is the same as Exp.1. It only replaced the neutral schematic faces with

Result

Result

• The average PSS was 7.17 ms, which differed significantly from zero, t(15) 2.46, p <.025, once again indicating a prior entry effect for the threatening face.

Experiment 4

Experiment 4

• To further investigate whether the prior entry effect found in Experiment 2 was due to low-level featural differences between the neutral and angry face.

Exp. 4 預期結果與其假設之間的關係

• (1) If results from Experiment 2 were in fact driven by holistic emotional processing.

(2) If inverting a face stimulus breaks down its holistic processing.

• prior entry effects should be eliminated in the present experiment.

換句話說

• If previous results (Exp.2) were due to low-level featural confounds

• A prior entry effect should still be observed

• In addition, if participants still report that the inverted angry face produces prior entry, this could also indicate a response bias present in previous experiments.

(當不確定就選比較interesting的臉。)

Result

Result

• The average PSS was calculated to be

• 1.28 ms, which was nonsignificant, t(13) <1, indicating no reliable prior entry effect for either of the inverted face stimuli.

因為visual prior effect沒有了，所以支持 Exp.2是holistic processing prior entry for the angry face

can be attributed to holistic processing.

Experiment 5

• Why did Exp. 5?

• 前面都是用schematic face, 不確定推論是否可以類推到真人的臉。

• 和Exp. 2一樣，只是現在換成真人的臉

Hypothesis

• A realistic threatening face should show visual

prior entry when contrasted against a realistic neutral face.

Procedure

• 和實驗二同

Result實驗五的結果 實驗二的結果

用真人的臉，所造成的shift會比用略圖的臉更大。表示visual prior effect在真人的臉會更強。

Result

• The average PSS was 18.26 ms, which differed significantly from zero, t(11) 3.78, p .003, showing that prior entry for facial displays of threat extend to human face stimuli.

Experiment 6

• 為了要排除response bias

• 所以改變了指導語。

-- 要受試者說”哪一個是之後才出現的?”

Procedure

• 引用 Exp.5，只有指導語不同。

實驗五 實驗六

Result

• The average PSS was calculated to be 7.66 ms, which differed significantly from zero, t(13) < 2.85, p <.017, again demonstrating prior entry for human angry faces.

Compare Ex.1~Ex.6

Visual prior entries in milliseconds are displayed for Experiments

1 through 6, representing the observed attentional capture effects.

Conclusion

Conclusion

• The authors demonstrate, using a novel TOJ paradigm without cues, that displays of faces

and facial threat show visual prior entry effects.