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Cortical processing and perceived timing.

Arnold DH, Wilcock P - Proc. Biol. Sci. (2007)

Bottom Line: We find that observers require longer stimulus exposures to detect small, relative to larger, disparity changes; observers are slower to react to smaller disparity changes and observers misperceive smaller disparity changes as being perceptually delayed.Interestingly, disparity magnitude influenced perceived timing more dramatically than it did stimulus change detection.Our data therefore suggest that perceived timing is both influenced by cortical processing and is shaped by sensory analyses subsequent to those that are minimally necessary for stimulus change perception.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia. darnold@psy.uq.edu.au

ABSTRACT
As of yet, it is unclear how we determine relative perceived timing. One controversial suggestion is that timing perception might be related to when analyses are completed in the cortex of the brain. An alternate proposal suggests that perceived timing is instead related to the point in time at which cortical analyses commence. Accordingly, timing illusions should not occur owing to cortical analyses, but they could occur if there were differential delays between signals reaching cortex. Resolution of this controversy therefore requires that the contributions of cortical processing be isolated from the influence of subcortical activity. Here, we have done this by using binocular disparity changes, which are known to be detected via analyses that originate in cortex. We find that observers require longer stimulus exposures to detect small, relative to larger, disparity changes; observers are slower to react to smaller disparity changes and observers misperceive smaller disparity changes as being perceptually delayed. Interestingly, disparity magnitude influenced perceived timing more dramatically than it did stimulus change detection. Our data therefore suggest that perceived timing is both influenced by cortical processing and is shaped by sensory analyses subsequent to those that are minimally necessary for stimulus change perception.

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Related in: MedlinePlus

Scatter plots (a,c,e) show data for four individual observers. Bar graphs (b,d,f) show data averaged across these observers. Error bars show ±1 s.e. (a) Scatter plot showing temporal detection threshold differences (TT differences), relative to temporal threshold estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (b) Average TT differences. (c) Scatter plot showing RT differences, relative to RTs for disparity changes of 0.07°, as a function of disparity change magnitude. (d) Average RT differences. (e) Scatter plot showing perceived synchrony (PS) differences, relative to PS estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (f) Average PS differences.
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fig1: Scatter plots (a,c,e) show data for four individual observers. Bar graphs (b,d,f) show data averaged across these observers. Error bars show ±1 s.e. (a) Scatter plot showing temporal detection threshold differences (TT differences), relative to temporal threshold estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (b) Average TT differences. (c) Scatter plot showing RT differences, relative to RTs for disparity changes of 0.07°, as a function of disparity change magnitude. (d) Average RT differences. (e) Scatter plot showing perceived synchrony (PS) differences, relative to PS estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (f) Average PS differences.

Mentions: Data from each run of 500 trials in experiment 2 provided RT distributions for each of the four magnitudes of horizontal disparity change (0.07°, 0.14°, 0.21° and 0.28°). RT differences were calculated relative to the observers’ RTs for the smallest disparity signal. RT differences as a function of disparity magnitude are shown in figure 1c,d.


Cortical processing and perceived timing.

Arnold DH, Wilcock P - Proc. Biol. Sci. (2007)

Scatter plots (a,c,e) show data for four individual observers. Bar graphs (b,d,f) show data averaged across these observers. Error bars show ±1 s.e. (a) Scatter plot showing temporal detection threshold differences (TT differences), relative to temporal threshold estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (b) Average TT differences. (c) Scatter plot showing RT differences, relative to RTs for disparity changes of 0.07°, as a function of disparity change magnitude. (d) Average RT differences. (e) Scatter plot showing perceived synchrony (PS) differences, relative to PS estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (f) Average PS differences.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211513&req=5

fig1: Scatter plots (a,c,e) show data for four individual observers. Bar graphs (b,d,f) show data averaged across these observers. Error bars show ±1 s.e. (a) Scatter plot showing temporal detection threshold differences (TT differences), relative to temporal threshold estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (b) Average TT differences. (c) Scatter plot showing RT differences, relative to RTs for disparity changes of 0.07°, as a function of disparity change magnitude. (d) Average RT differences. (e) Scatter plot showing perceived synchrony (PS) differences, relative to PS estimates concerning disparity changes of 0.07°, as a function of disparity change magnitude. (f) Average PS differences.
Mentions: Data from each run of 500 trials in experiment 2 provided RT distributions for each of the four magnitudes of horizontal disparity change (0.07°, 0.14°, 0.21° and 0.28°). RT differences were calculated relative to the observers’ RTs for the smallest disparity signal. RT differences as a function of disparity magnitude are shown in figure 1c,d.

Bottom Line: We find that observers require longer stimulus exposures to detect small, relative to larger, disparity changes; observers are slower to react to smaller disparity changes and observers misperceive smaller disparity changes as being perceptually delayed.Interestingly, disparity magnitude influenced perceived timing more dramatically than it did stimulus change detection.Our data therefore suggest that perceived timing is both influenced by cortical processing and is shaped by sensory analyses subsequent to those that are minimally necessary for stimulus change perception.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, The University of Queensland, St Lucia, Queensland 4072, Australia. darnold@psy.uq.edu.au

ABSTRACT
As of yet, it is unclear how we determine relative perceived timing. One controversial suggestion is that timing perception might be related to when analyses are completed in the cortex of the brain. An alternate proposal suggests that perceived timing is instead related to the point in time at which cortical analyses commence. Accordingly, timing illusions should not occur owing to cortical analyses, but they could occur if there were differential delays between signals reaching cortex. Resolution of this controversy therefore requires that the contributions of cortical processing be isolated from the influence of subcortical activity. Here, we have done this by using binocular disparity changes, which are known to be detected via analyses that originate in cortex. We find that observers require longer stimulus exposures to detect small, relative to larger, disparity changes; observers are slower to react to smaller disparity changes and observers misperceive smaller disparity changes as being perceptually delayed. Interestingly, disparity magnitude influenced perceived timing more dramatically than it did stimulus change detection. Our data therefore suggest that perceived timing is both influenced by cortical processing and is shaped by sensory analyses subsequent to those that are minimally necessary for stimulus change perception.

Show MeSH
Related in: MedlinePlus