Incentive value and spatial certainty combine additively to determine visual priorities

K.G Garner,J.E Raymond,H Bowman

doi:10.3758/s13414-020-02124-w

K.G Garner, J.E Raymond + Show 1 more

Open Access

https://doi.org/10.3758/s13414-020-02124-w

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Abstract

How does the brain combine information predictive of the value of a visually guided task (incentive value) with information predictive of where task-relevant stimuli may occur (spatial certainty)? Human behavioural evidence indicates that these two predictions may be combined additively to bias visual selection (Additive Hypothesis), whereas neuroeconomic studies posit that they may be multiplicatively combined (Expected Value Hypothesis). We sought to adjudicate between these two alternatives. Participants viewed two coloured placeholders that specified the potential value of correctly identifying an imminent letter target if it appeared in that placeholder. Then, prior to the target’s presentation, an endogenous spatial cue was presented indicating the target’s more likely location. Spatial cues were parametrically manipulated with regard to the information gained (in bits). Across two experiments, performance was better for targets appearing in high versus low value placeholders and better when targets appeared in validly cued locations. Interestingly, as shown with a Bayesian model selection approach, these effects did not interact, clearly supporting the Additive Hypothesis. Even when conditions were adjusted to increase the optimality of a multiplicative operation, support for it remained. These findings refute recent theories that expected value computations are the singular mechanism driving the deployment of endogenous spatial attention. Instead, incentive value and spatial certainty seem to act independently to influence visual selection.

Highlights

Humans are good at learning that specific sensory information, or cues, can predict subsequent events
Results were evaluated using a Bayesian model selection approach. We found in both Experiments that the influence of incentive value and spatial certainty remains additive across all tested levels of spatial certainty, arguing against the Expected Value Hypothesis
Previous studies show that learning can direct the sampling of sensory information to optimise reward accrual (Drugowitsch et al, 2015; Kiani & Shadlen, 2009; Serences, 2008), allowing the possibility that a reward structure favouring an expected value operation may be sufficient to modulate the additive influence of incentive value and spatial certainty

Summary

Introduction

Humans are good at learning that specific sensory information, or cues, can predict subsequent events. Unclear is how multiple concurrent sensory cues, each associated with and predictive of specific consequent outcomes, are combined to influence visual selection. Multiple endogenous sources appear to exert parallel influences on visual selection (see Hutchinson & TurkBrowne, 2012, for a review), even when learned information is antithetical to the current goals as defined by the task-set (see Awh et al, 2012, for a review). We seek to understand how selection biases that stem from learned associations between sensory cues and reward outcomes (incentive value) are combined with biases driven by associations between sensory cues and the probable location of task-relevant target information (spatial certainty)

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