Abstract
Humans and animals can integrate sensory evidence from various sources to make decisions in a statistically near-optimal manner, provided that the stimulus presentation time is fixed across trials. Little is known about whether optimality is preserved when subjects can choose when to make a decision (reaction-time task), nor when sensory inputs have time-varying reliability. Using a reaction-time version of a visual/vestibular heading discrimination task, we show that behavior is clearly sub-optimal when quantified with traditional optimality metrics that ignore reaction times. We created a computational model that accumulates evidence optimally across both cues and time, and trades off accuracy with decision speed. This model quantitatively explains subjects's choices and reaction times, supporting the hypothesis that subjects do, in fact, accumulate evidence optimally over time and across sensory modalities, even when the reaction time is under the subject's control.
Highlights
Effective decision making in an uncertain, rapidly changing environment requires optimal use of all information available to the decision-maker
Using a reaction-time version of a multimodal heading discrimination task, we demonstrate here that human performance is markedly suboptimal when evaluated with standard criteria that ignore reaction times
In contrast to previous tasks conducted with the same apparatus (Fetsch et al, 2009; Gu et al, 2010), subjects did not have to wait until the end of the stimulus presentation, but were allowed to respond at any time throughout the trial, which lasted up to 2 s
Summary
Effective decision making in an uncertain, rapidly changing environment requires optimal use of all information available to the decision-maker. Numerous previous studies have examined how integrating multiple sensory cues—either within or across sensory modalities—alters perceptual sensitivity (van Beers et al, 1996; Ernst and Banks, 2002; Battaglia et al, 2003; Fetsch et al, 2009) These studies generally reveal that subjects' ability to discriminate among stimuli improves when multiple sensory cues are available, such as visual and tactile (van Beers et al, 1996; Ernst and Banks, 2002), visual and auditory (Battaglia et al, 2003), or visual and vestibular (Fetsch et al, 2009) cues. By contrast, subjects usually choose for themselves when they have gathered enough information to make a decision In such contexts, it is possible that subjects integrate multiple cues to gain speed or to increase their proportion of correct responses (or some combination of effects), and it is unknown whether standard criteria for optimal cue integration apply. The conventional framework for optimal cue integration is not applicable to behaviors in which decision times are under subjects' control
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
