August 2016
Volume 16, Issue 12
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2016
Spatial Probability Improves Detection, Orientation Probability Improves Precision: Modelling as Neural Gain versus Tuning
Author Affiliations
  • Syaheed Jabar
    Department of Psychology, University of Waterloo
  • Britt Anderson
    Department of Psychology, University of Waterloo
Journal of Vision September 2016, Vol.16, 894. doi:
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      Syaheed Jabar, Britt Anderson; Spatial Probability Improves Detection, Orientation Probability Improves Precision: Modelling as Neural Gain versus Tuning. Journal of Vision 2016;16(12):894.

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      © ARVO (1962-2015); The Authors (2016-present)

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Frequent targets are detected faster, probable locations searched earlier, and likely orientations estimated more precisely. As attentional manipulations often convey probabilistic cues about where or what stimuli are likely to appear, is it the case that probability effects and attentional effects are largely one and the same? If true, probability effects for space and features should be distinct as they are for attentional cues, e.g. spatial attention has been linked to changes in neuronal gain, while feature-based attention is thought to affect neuronal tuning. To examine dissociations in spatial versus featural probability, we had participants report both location and orientation of gratings, while location or tilt probabilities were independently manipulated. While orientation probability affected the precision of orientation reports, spatial probability only modulated the likelihood of stimulus detection. Our results demonstrate that even when no physical attentional cues are present, acquired probabilistic information on space versus orientation leads to separable 'attention-like' effects on behavior. These behavioral results are consistent with current theories of attentional effects at the neuronal level. We used population vector coding to implement spatial probability as an orientation agnostic increase in the gain of orientation responsive neurons and orientation probability as a change in orientation selective tuning. The result is that total neural signal is boosted for probable locations, but that the perceptual systems' sensitivity to orientations is not affected, consistent with the behavioral finding that spatial probability only affects detection and not precision. By contrast, having orientation probability affected tuning results in orientation sensitivity and interacted with innate perceptual biases that can also be modeled as tuning differences. Together these results support the claim that many attentional effects can be more directly explained as probability effects, and that the mechanism of probability effects are implemented by adjustments in the gain and tuning of selectively responsive neurons.

Meeting abstract presented at VSS 2016


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