Working memory paradox: Using working memory distorts … · 2020. 6. 19. · Working memory...
Transcript of Working memory paradox: Using working memory distorts … · 2020. 6. 19. · Working memory...
Working memory paradox: Using working memory distorts working memoryKeisuke Fukuda1,2, April E. Pereira3, Joseph M. Saito2, Hiroyuki Tsubomi4, & Gi-Yeul Bae5
1University of Toronto Mississauga, 2University of Toronto, 3University of Waterloo,4University of Toyama, & 5Arizona State University
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Memory item Memory itemSame-side probe Opposite-side probe
1st probe pair2nd probe pair
Sim
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“Remember”
“Remember”
“Recall” “Adjust” “Confidence?”
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“Recall” “Adjust” “Confidence?”
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+800ms delay1600ms
+ 800ms delay Until response Until response Until response
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2000ms+ 500ms delay Until response Until response
“More similar?” “More similar?”
“Remember”
“Remember”
“Recall” “Adjust” “Confidence?”
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“Recall” “Adjust” “Confidence?”
1 2 3Until response
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Signed response offset (°)
Signed response offset (°)
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D. Prediction: Similarity judgment biases VWM H. Prediction: Perceived similarity induces attraction bias
I. Attraction or repulsion? J. Physical or perceived similarity?
C. Exp 1: Inducing and cancelling VWM bias by similarity judgments G. Exp 2: Examining the underlying mechanism of VWM bias K. Exp 3: Predicting biasA. Introduction
B. Stimuli L. DiscussionE. VWM bias? F. Driven by low-confidence reports?
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If using VWM for similarity judgments distorts VWM,the response offset distribution should be
systematically biased in the same-side probe condition.
Furthermore, the systematic bias should be‘cancelled out’
in the opposite-side probe condition.
Confidence report: 1 = High confidence, 2 = Low confidence, 3 = No confidenceProbe range: Similar probe = 16º-45º away from target, Dissimilar probe = 180º away from similar probe
Confidence report: 1 = High confidence, 2 = Low confidence, 3 = No confidenceProbe range: Similar probe = 16º-105º away from target
If a similar probe attracts VWM representations,VWM should be biased toward the probe
when it is judged as “similar” to VWM.
If perceived similarity drives the VWM bias,physically-identical probes should produce different
VWM bias depending on the perceived similarity.
Probe
“Similar!”
Attraction bias
Probe
“Dissimilar!”
Negligible bias
Probe
“Similar!”
Larger bias
Probe
“Dissimilar!”
Smaller bias
Signed response offset (°) for HC responses
Signed response offset (°) for HC responses
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Similarity judgments bias VWM toward a similar probe.
VWM bias occurs even whenparticipants are highly confident (HC) in their VWM. VWM is attracted toward a probe.
Signed response offset (°) for HC responses
Signed response offset (°) for HC responses
Perceived similarity, but not physical similarity,drives VWM bias.
Individuals with lower VWM precisionare more vulnerable to VWM bias.
The primary goal of visual working memory (VWM) is to accurately maintain a limited amount of task-relevant visual information in mind so that it can be used to guide our behavior.
Studies have examined the robustness of VWM representations by imposing task-irrelevant distractions duringencoding and maintenance.
However, no studies have examined whether VWM representations remain intact when they are used to accomplish a directly-relevant task.
Considering that many tasks in real life require repeated usage of the same VWM representation (e.g., visual search), it is imperative to investigate whether VWM survives its usage without asystematic distortion.
Is VWM distorted when it isused for a task-relevantperceptual comparison?
Research Question:
VWM representation is attracted toward new visual input especially when the input is perceived to be similar to VWM representation (VWM bias).
Cancellation of VWM bias in theopposite-side probe condition (Exp. 1) and the lack of repulsion bias following dissimilar judgments (Exp. 2)demonstrate that VWM encoding noise cannot explain VWM bias, thusimplicating the causal role of similarity judgments.
Individuals with lower VWM precisionexhibit larger VWM bias.
These findings can be explained by ahypothesis that representationalintegration between VWM and new“perceived-to-be-similar” visual inputunderlies VWM bias.
Circular Color Space(Zhang & Luck, 2008)
Circular Shape Space(Li et al., 2017)
Li, A. Y., Liang, J. C., Lee, A. C. H., & Barense, M. D. (2019). The validated circular shape space: Quanti-fying the visual similarity of shape. J Exp Psychol Gen. doi:10.1037/xge0000693Zhang, W., & Luck, S. J. (2008). Discrete fixed-resolution representations in visual working memory. Nature, 453(7192), 233-235. doi:10.1038/nature06860
BaselineSame-sideOpposite-side
BaselineSame-sideOpposite-side
Mean signed response offsetSame-side: 6.5° ***Opposite-side: -1.5° *
Signed response offset(°):positive offset = offset toward the first similar probe
Mean signed response offsetSame-side: 6.4° ***Opposite-side: 0.0°
Mean signed response offsetSame-side: 6.1° ***Opposite-side: -1.3° *
BaselineSame-sideOpposite-side
Mean signed response offsetSame-side: 5.6° ***Opposite-side: -0.4°
p-value* < 0.05** < 0.01*** < 0.001
p-value* < 0.05** < 0.01*** < 0.001
BaselineSimilarDissimilar
Mean signed response offsetSimilar: 8.1° ***Dissimilar: 3.0° ***Sim > Dissimilar **
Mean signed response offsetSimilar: 7.6° ***Dissimilar: 2.9° ***Sim > Dissimilar **
BaselineSimilarDissimilar
BaselineSimilarDissimilar
BaselineSimilarDissimilar
Mean signed response offsetSimilar: 11.4° ***Dissimilar: 1.3°Sim > Dissimilar ***
Mean signed response offsetSimilar: 9.9° ***Dissimilar: 2.5° **Sim > Dissimilar **
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sVWM VWM VWM VWM
Signed response offset(°):positive offset = offset toward the first similar probe
Signed response offset(°):positive offset = offset toward probe
Signed response offset(°):positive offset = offset toward probe
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P|sP,κP )Memory item:
p(xM|sM,κM)Probe item:
p(xP|sP,κP)Joint density:p(xM|sM,κM)p(x
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Representational integration hypothesis:VWM bias is caused by representational
integration between VWM and perceptually-similar probe.
r = -0.37p < 0.001
r = -0.33p < 0.001
Color Shape
If so, individuals with lower VWM precision should show larger VWM bias due to
larger integration window.
Similar probe = 16º-45º away from targetDissimilar probe = 180º away from similar probe
N = 28 N = 16
N = 110