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The spatial and temporal construction of confidence in the visual scene.

Graziano M, Sigman M - PLoS ONE (2009)

Bottom Line: Here we compared the dynamics of objective performance with a measure of subjective report and we observed that 1) Objective performance beyond explicit subjective reports (blindsight) was significantly more pronounced within a short temporal interval and within specific locations of the visual field which were robust across sessions 2) High confidence errors (false beliefs) were largely confined to a small spatial window neighboring the cue.The size of this window did not change in time 3) Subjective confidence showed a moderate but consistent decrease with time, independent of all other experimental factors.Our study allowed us to asses quantitatively the temporal and spatial access to an objective response and to subjective reports.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, Integrative Neuroscience Laboratory, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Human subjects can report many items of a cluttered field a few hundred milliseconds after stimulus presentation. This memory decays rapidly and after a second only 3 or 4 items can be stored in working memory. Here we compared the dynamics of objective performance with a measure of subjective report and we observed that 1) Objective performance beyond explicit subjective reports (blindsight) was significantly more pronounced within a short temporal interval and within specific locations of the visual field which were robust across sessions 2) High confidence errors (false beliefs) were largely confined to a small spatial window neighboring the cue. The size of this window did not change in time 3) Subjective confidence showed a moderate but consistent decrease with time, independent of all other experimental factors. Our study allowed us to asses quantitatively the temporal and spatial access to an objective response and to subjective reports.

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Spatial biases in response distributions and subjective confidence.A) Left panels: Mean performance (p*) across positions for each subject. Center and Rigth panels: Probability of responding to a specific position in the array (independently of the position of the cue). Center: Each column corresponds to a location in the array (Nth column refers to N o'clock position. Each line corresponds to a different session. Right: Data collapsed across all sessions. B) Top Panel: Probability of responding to the location (i, in columns) given that the cue was in location (j, in lines), P(i,j). The matrix P approaches the diagonal (correct responses) for increasing levels of subjective confidence. Bottom panel: P in a polar representation for the lowest and highest subjective confidence. Mutual information of the distributions of the position of the cue and of responded letters increases with confidence but does not saturate even for the highest confidence values.
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pone-0004909-g003: Spatial biases in response distributions and subjective confidence.A) Left panels: Mean performance (p*) across positions for each subject. Center and Rigth panels: Probability of responding to a specific position in the array (independently of the position of the cue). Center: Each column corresponds to a location in the array (Nth column refers to N o'clock position. Each line corresponds to a different session. Right: Data collapsed across all sessions. B) Top Panel: Probability of responding to the location (i, in columns) given that the cue was in location (j, in lines), P(i,j). The matrix P approaches the diagonal (correct responses) for increasing levels of subjective confidence. Bottom panel: P in a polar representation for the lowest and highest subjective confidence. Mutual information of the distributions of the position of the cue and of responded letters increases with confidence but does not saturate even for the highest confidence values.

Mentions: As found in previous studies, here we observed consistent differences in performance as a function of the position of the cue, even in the absence of any task-related positions specificity, since the cue appeared with equal probability in all locations [14]. The left panels of Figure 3A show the performance for each individual subject as a function of the location within the array, grouping the data across all ISI values and letter identities. This bias in performance was largely determined by a bias in the response – as indicated by the maps of the position of the responded letter (regardless of the position of the cue) which were very heavily weighted towards certain specific positions of the array (Figure 3A, right panels). To assess the reliability of this measurement, and to investigate possible mechanisms which may lead to the spatial inhomogeneity in performance, we explored the variability of the spatial maps of responded letter for each individual subject in different experimental sessions (Figure 3A, center panels). These results showed that, for each subject, the pattern of responses showed consistent regions with very high probability of response (for instance participant 2 has a very strong bias to report the stimulus presented at 3 and 9 o'clock). We also found several positions which were virtually “blind” to both participants, particularly in the lower hemi-field. This response bias was remarkably stable as can be seen by the analysis of responses for different experimental sessions, each performed in a different day. Importantly, the position bias seems to be completely unconscious as participants were unaware of the fact that they were responding with unusually high probability to letters in specific locations of the array.


The spatial and temporal construction of confidence in the visual scene.

Graziano M, Sigman M - PLoS ONE (2009)

Spatial biases in response distributions and subjective confidence.A) Left panels: Mean performance (p*) across positions for each subject. Center and Rigth panels: Probability of responding to a specific position in the array (independently of the position of the cue). Center: Each column corresponds to a location in the array (Nth column refers to N o'clock position. Each line corresponds to a different session. Right: Data collapsed across all sessions. B) Top Panel: Probability of responding to the location (i, in columns) given that the cue was in location (j, in lines), P(i,j). The matrix P approaches the diagonal (correct responses) for increasing levels of subjective confidence. Bottom panel: P in a polar representation for the lowest and highest subjective confidence. Mutual information of the distributions of the position of the cue and of responded letters increases with confidence but does not saturate even for the highest confidence values.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2654151&req=5

pone-0004909-g003: Spatial biases in response distributions and subjective confidence.A) Left panels: Mean performance (p*) across positions for each subject. Center and Rigth panels: Probability of responding to a specific position in the array (independently of the position of the cue). Center: Each column corresponds to a location in the array (Nth column refers to N o'clock position. Each line corresponds to a different session. Right: Data collapsed across all sessions. B) Top Panel: Probability of responding to the location (i, in columns) given that the cue was in location (j, in lines), P(i,j). The matrix P approaches the diagonal (correct responses) for increasing levels of subjective confidence. Bottom panel: P in a polar representation for the lowest and highest subjective confidence. Mutual information of the distributions of the position of the cue and of responded letters increases with confidence but does not saturate even for the highest confidence values.
Mentions: As found in previous studies, here we observed consistent differences in performance as a function of the position of the cue, even in the absence of any task-related positions specificity, since the cue appeared with equal probability in all locations [14]. The left panels of Figure 3A show the performance for each individual subject as a function of the location within the array, grouping the data across all ISI values and letter identities. This bias in performance was largely determined by a bias in the response – as indicated by the maps of the position of the responded letter (regardless of the position of the cue) which were very heavily weighted towards certain specific positions of the array (Figure 3A, right panels). To assess the reliability of this measurement, and to investigate possible mechanisms which may lead to the spatial inhomogeneity in performance, we explored the variability of the spatial maps of responded letter for each individual subject in different experimental sessions (Figure 3A, center panels). These results showed that, for each subject, the pattern of responses showed consistent regions with very high probability of response (for instance participant 2 has a very strong bias to report the stimulus presented at 3 and 9 o'clock). We also found several positions which were virtually “blind” to both participants, particularly in the lower hemi-field. This response bias was remarkably stable as can be seen by the analysis of responses for different experimental sessions, each performed in a different day. Importantly, the position bias seems to be completely unconscious as participants were unaware of the fact that they were responding with unusually high probability to letters in specific locations of the array.

Bottom Line: Here we compared the dynamics of objective performance with a measure of subjective report and we observed that 1) Objective performance beyond explicit subjective reports (blindsight) was significantly more pronounced within a short temporal interval and within specific locations of the visual field which were robust across sessions 2) High confidence errors (false beliefs) were largely confined to a small spatial window neighboring the cue.The size of this window did not change in time 3) Subjective confidence showed a moderate but consistent decrease with time, independent of all other experimental factors.Our study allowed us to asses quantitatively the temporal and spatial access to an objective response and to subjective reports.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, Integrative Neuroscience Laboratory, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Human subjects can report many items of a cluttered field a few hundred milliseconds after stimulus presentation. This memory decays rapidly and after a second only 3 or 4 items can be stored in working memory. Here we compared the dynamics of objective performance with a measure of subjective report and we observed that 1) Objective performance beyond explicit subjective reports (blindsight) was significantly more pronounced within a short temporal interval and within specific locations of the visual field which were robust across sessions 2) High confidence errors (false beliefs) were largely confined to a small spatial window neighboring the cue. The size of this window did not change in time 3) Subjective confidence showed a moderate but consistent decrease with time, independent of all other experimental factors. Our study allowed us to asses quantitatively the temporal and spatial access to an objective response and to subjective reports.

Show MeSH
Related in: MedlinePlus