Dataset Information

Simultaneous modeling of visual saliency and value computation improves predictions of economic choice.

ABSTRACT: Many decisions we make require visually identifying and evaluating numerous alternatives quickly. These usually vary in reward, or value, and in low-level visual properties, such as saliency. Both saliency and value influence the final decision. In particular, saliency affects fixation locations and durations, which are predictive of choices. However, it is unknown how saliency propagates to the final decision. Moreover, the relative influence of saliency and value is unclear. Here we address these questions with an integrated model that combines a perceptual decision process about where and when to look with an economic decision process about what to choose. The perceptual decision process is modeled as a drift-diffusion model (DDM) process for each alternative. Using psychophysical data from a multiple-alternative, forced-choice task, in which subjects have to pick one food item from a crowded display via eye movements, we test four models where each DDM process is driven by (i) saliency or (ii) value alone or (iii) an additive or (iv) a multiplicative combination of both. We find that models including both saliency and value weighted in a one-third to two-thirds ratio (saliency-to-value) significantly outperform models based on either quantity alone. These eye fixation patterns modulate an economic decision process, also described as a DDM process driven by value. Our combined model quantitatively explains fixation patterns and choices with similar or better accuracy than previous models, suggesting that visual saliency has a smaller, but significant, influence than value and that saliency affects choices indirectly through perceptual decisions that modulate economic decisions.

SUBMITTER: Towal RB

PROVIDER: S-EPMC3791693 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Simultaneous modeling of visual saliency and value computation improves predictions of economic choice.

Towal R Blythe RB Mormann Milica M Koch Christof C

Proceedings of the National Academy of Sciences of the United States of America 20130909 40

Many decisions we make require visually identifying and evaluating numerous alternatives quickly. These usually vary in reward, or value, and in low-level visual properties, such as saliency. Both saliency and value influence the final decision. In particular, saliency affects fixation locations and durations, which are predictive of choices. However, it is unknown how saliency propagates to the final decision. Moreover, the relative influence of saliency and value is unclear. Here we address th ...[more]

PMID: 24019496

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Project description:BackgroundPreclinical studies into drug vs. nondrug choice have emerged to better model and investigate the neurobehavioral mechanisms underlying drug preference. Current literature has suggested that drugs of abuse have inherently low value, thus promoting food preference. Herein, we examined remifentanil vs. food choice to test both the relative value hypothesis and the 'direct effects' (pharmacological effects of drugs on alternative reinforcers) hypothesis of opioid preference.MethodsAdult male rats were trained under two choice procedures (controlled vs. uncontrolled reinforcer frequency) for remifentanil vs. food choice. Furthermore, a series of procedural manipulations known to affect drug reinforcement were tested under both choice procedures. Using remifentanil self-administration data, pharmacokinetic profiles were calculated and analyzed to determine if opioid intake was related to opioid preference.ResultsBoth choice procedures produced dose-dependent preference. Moreover, procedural manipulations produced comparable changes in remifentanil preference under both choice procedures. In addition, calculated pharmacokinetic data revealed that preference was dissociable from intake under the controlled reinforcer frequency choice procedure.ConclusionsWhen compared to the 'direct effects' hypothesis, remifentanil preference was better predicted by the relative value hypothesis, formalized in generalized matching. Use of a controlled reinforcer frequency schedule successfully removed the drug preference-intake confound found in most drug-choice procedures. Importantly, drug preference under the controlled reinforcer frequency schedule remained sensitive to procedural manipulations known to affect drug reinforcement. Thus, given that differential drug intake itself affects neurobiological measurements, future use of controlled reinforcer frequency schedules may help to better isolate the neurobehavioral mechanisms that mediate opioid preference.

Project description:BackgroundDuring visual exploration or free-view, gaze positioning is largely determined by the tendency to maximize visual saliency: more salient locations are more likely to be fixated. However, when visual input is completely irrelevant for performance, such as with non-visual tasks, this saliency maximization strategy may be less advantageous and potentially even disruptive for task-performance. Here, we examined whether visual saliency remains a strong driving force in determining gaze positions even in non-visual tasks. We tested three alternative hypotheses: a) That saliency is disadvantageous for non-visual tasks and therefore gaze would tend to shift away from it and towards non-salient locations; b) That saliency is irrelevant during non-visual tasks and therefore gaze would not be directed towards it but also not away-from it; c) That saliency maximization is a strong behavioral drive that would prevail even during non-visual tasks.MethodsGaze position was monitored as participants performed visual or non-visual tasks while they were presented with complex or simple images. The effect of attentional demands was examined by comparing an easy non-visual task with a more difficult one.ResultsExploratory behavior was evident, regardless of task difficulty, even when the task was non-visual and the visual input was entirely irrelevant. The observed exploratory behaviors included a strong tendency to fixate salient locations, central fixation bias and a gradual reduction in saliency for later fixations. These exploratory behaviors were spatially similar to those of an explicit visual exploration task but they were, nevertheless, attenuated. Temporal differences were also found: in the non-visual task there were longer fixations and later first fixations than in the visual task, reflecting slower visual sampling in this task.ConclusionWe conclude that in the presence of a rich visual environment, visual exploration is evident even when there is no explicit instruction to explore. Compared to visually motivated tasks, exploration in non-visual tasks follows similar selection mechanisms, but occurs at a lower rate. This is consistent with the view that the non-visual task is the equivalent of a dual-task: it combines the instructed task with an uninstructed, perhaps even mandatory, exploratory behavior.

Project description:Under fast viewing conditions, the visual system extracts salient and simplified representations of complex visual scenes. Saccadic eye movements optimize such visual analysis through the dynamic sampling of the most informative and salient regions in the scene. However, a general definition of saliency, as well as its role for natural active vision, is still a matter for discussion. Following the general idea that visual saliency may be based on the amount of local information, a recent constrained maximum-entropy model of early vision, applied to natural images, extracts a set of local optimal information-carriers, as candidate salient features. These optimal features proved to be more informative than others in fast vision, when embedded in simplified sketches of natural images. In the present study, for the first time, these features were presented in isolation, to investigate whether they can be visually more salient than other non-optimal features, even in the absence of any meaningful global arrangement (contour, line, etc.). In four psychophysics experiments, fast discriminability of a compound of optimal features (target) in comparison with a similar compound of non-optimal features (distractor) was measured as a function of their number and contrast. Results showed that the saliency predictions from the constrained maximum-entropy model are well verified in the data, even when the optimal features are presented in smaller numbers or at lower contrast. In the eye movements experiment, the target and the distractor compounds were presented in the periphery at different angles. Participants were asked to perform a simple choice-saccade task. Results showed that saccades can select informative optimal features spatially interleaved with non-optimal features even at the shortest latencies. Saccades' choice accuracy and landing position precision improved with SNR. In conclusion, the optimal features predicted by the reference model, turn out to be more salient than others, despite the lack of any clues coming from a global meaningful structure, suggesting that they get preferential treatment during fast image analysis. Also, peripheral fast visual processing of these informative local features is able to guide gaze orientation. We speculate that active vision is efficiently adapted to maximize information in natural visual scenes.

Dataset Information

Simultaneous modeling of visual saliency and value computation improves predictions of economic choice.

Publications

Simultaneous modeling of visual saliency and value computation improves predictions of economic choice.

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