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Primary Visual Cortex as a Saliency Map: A Parameter-Free Prediction and Its Test by Behavioral Data.

Zhaoping L, Zhe L - PLoS Comput. Biol. (2015)

Bottom Line: This hypothesis has so far provided only qualitative predictions and their confirmations.A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs.Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functions like visual decoding and endogenous attention.

View Article: PubMed Central - PubMed

Affiliation: University College London, London, United Kingdom.

ABSTRACT
It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. We report this hypothesis' first quantitative prediction, derived without free parameters, and its confirmation by human behavioral data. The hypothesis provides a direct link between V1 neural responses to a visual location and the saliency of that location to guide attention exogenously. In a visual input containing many bars, one of them saliently different from all the other bars which are identical to each other, saliency at the singleton's location can be measured by the shortness of the reaction time in a visual search for singletons. The hypothesis predicts quantitatively the whole distribution of the reaction times to find a singleton unique in color, orientation, and motion direction from the reaction times to find other types of singletons. The prediction matches human reaction time data. A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs. Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functions like visual decoding and endogenous attention.

No MeSH data available.


Diagram outlining the methods to test each of our race equalities, e.g., .The details of various components, in boxes (1)-(8), are described in the text.
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pcbi.1004375.g011: Diagram outlining the methods to test each of our race equalities, e.g., .The details of various components, in boxes (1)-(8), are described in the text.

Mentions: Briefly, a race equality, e.g., , is a hypothesis. It is used to predict the distribution of RTgoal, the designated type of reaction times in the equality (e.g., RTCO is the RTgoal for ), from the behaviorally observed distributions of the other reaction times in the equality. A distance D is then calculated between the predicted distribution and the behaviorally observed one of RTgoal. Typically D is non-zero even when a race equality does hold, since finite numbers of data samples can only approximately represent the underlying distributions of various reaction times. A statistical test is devised to give a p value, the probability that the D should be at least as big as observed if the hypothesis holds. A p > 0.05 is chosen to suggest that the race equality agrees with data. The details of the components of the hypothesis testing method, represented by the boxes in Fig 11, are described next.


Primary Visual Cortex as a Saliency Map: A Parameter-Free Prediction and Its Test by Behavioral Data.

Zhaoping L, Zhe L - PLoS Comput. Biol. (2015)

Diagram outlining the methods to test each of our race equalities, e.g., .The details of various components, in boxes (1)-(8), are described in the text.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595278&req=5

pcbi.1004375.g011: Diagram outlining the methods to test each of our race equalities, e.g., .The details of various components, in boxes (1)-(8), are described in the text.
Mentions: Briefly, a race equality, e.g., , is a hypothesis. It is used to predict the distribution of RTgoal, the designated type of reaction times in the equality (e.g., RTCO is the RTgoal for ), from the behaviorally observed distributions of the other reaction times in the equality. A distance D is then calculated between the predicted distribution and the behaviorally observed one of RTgoal. Typically D is non-zero even when a race equality does hold, since finite numbers of data samples can only approximately represent the underlying distributions of various reaction times. A statistical test is devised to give a p value, the probability that the D should be at least as big as observed if the hypothesis holds. A p > 0.05 is chosen to suggest that the race equality agrees with data. The details of the components of the hypothesis testing method, represented by the boxes in Fig 11, are described next.

Bottom Line: This hypothesis has so far provided only qualitative predictions and their confirmations.A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs.Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functions like visual decoding and endogenous attention.

View Article: PubMed Central - PubMed

Affiliation: University College London, London, United Kingdom.

ABSTRACT
It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. We report this hypothesis' first quantitative prediction, derived without free parameters, and its confirmation by human behavioral data. The hypothesis provides a direct link between V1 neural responses to a visual location and the saliency of that location to guide attention exogenously. In a visual input containing many bars, one of them saliently different from all the other bars which are identical to each other, saliency at the singleton's location can be measured by the shortness of the reaction time in a visual search for singletons. The hypothesis predicts quantitatively the whole distribution of the reaction times to find a singleton unique in color, orientation, and motion direction from the reaction times to find other types of singletons. The prediction matches human reaction time data. A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs. Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functions like visual decoding and endogenous attention.

No MeSH data available.