Reward learning and statistical learning independently influence attentional priority of salient distractors in visual search.

Existing research demonstrates different ways in which attentional prioritization of salient nontarget stimuli is shaped by prior experience: Reward learning renders signals of high-value outcomes more likely to capture attention than signals of low-value outcomes, whereas statistical learning can produce attentional suppression of the location in which salient distractor items are likely to appear. The current study combined manipulations of the value and location associated with salient distractors in visual search to investigate whether these different effects of selection history operate independently or interact to determine overall attentional prioritization of salient distractors. In Experiment 1, high-value and low-value distractors most frequently appeared in the same location; in Experiment 2, high-value and low-value distractors typically appeared in distinct locations. In both experiments, effects of distractor value and location were additive, suggesting that attention-promoting effects of value and attention-suppressing effects of statistical location-learning independently modulate overall attentional priority. Our findings are consistent with a view that sees attention as mediated by a common priority map that receives and integrates separate signals relating to physical salience and value, with signal suppression based on statistical learning determined by physical salience, but not incentive salience.

Awareness is necessary for attentional biases by location-reward association.

Many studies have reported attentional biases based on feature-reward associations. However, the effects of location-reward associations on attentional selection remain less well-understood. Unlike feature cases, a previous study that induced participants' awareness of the location-reward association by instructing them to look for a high-reward location has suggested the critical role of goal-driven manipulations in such associations. In this study, we investigated whether the reward effect occurred without goal-driven manipulations if participants were spontaneously aware of the location-reward association. We conducted three experiments using a visual search task that included four circles where participants received rewards; one possible target location was associated with a high reward, and another with a low reward. In Experiment 1, the target was presented among distractors, and participants had to search for the target. The results showed a faster reaction time in the high-reward rather than the low-reward locations only in participants aware of the location-reward association, even if they were not required to look for the association. Moreover, in Experiment 2, we replicated the main findings of Experiment 1, even when the target had an abrupt visual onset to restrict goal-driven manipulations. Furthermore, Experiment 3 confirmed that the effect observed in Experiment 2 could not be attributed to the initial eye position. These findings suggest that goal-driven manipulations are unnecessary for inducing reward biases to high-reward locations. We concluded that awareness of the association rather than goal-driven manipulations is crucial for the location-reward effect.

Pavlovian reward learning elicits attentional capture by reward-associated stimuli.

Feature-reward association elicits value-driven attentional capture (VDAC) regardless of the task relevance of associated features. What are the necessary conditions for feature-reward associations in VDAC? Recent studies claim that VDAC is based on Pavlovian conditioning. In this study, we manipulated the temporal relationships among feature, response, and reward in reward learning to elucidate the necessary components of VDAC. We presented reward-associated features in a variety of locations in a flanker task to form a color-reward association (training phase) and then tested VDAC in a subsequent visual search task (test phase). In Experiment 1, we showed reward-associated features in a task display requiring response selection and observed VDAC, consistent with most previous studies. In Experiment 2, features presented at a fixation display before a task display also induced VDAC. Moreover, in Experiment 3, we reduced the time interval between features and rewards so that features appeared after a task display and we obtained marginally significant VDAC. However, no VDAC was observed when features and rewards were simultaneously presented in a feedback display in Experiments 4 and 5, suggesting that a direct association between feature and reward is not sufficient for VDAC. These results are in favor of the idea that response selection does not mediate feature-reward association in VDAC. Moreover, the evidence suggests that the time interval of feature and reward is flexible with some restriction in the learning of feature-reward association. The present study supports the hypothesis that theories of Pavlovian conditioning can account for feature-reward association in VDAC.

Task-irrelevant stimulus-reward association induces value-driven attentional capture.

Rewards affect the deployment of visual attention in various situations. Evidence suggests that the stimulus associated with reward involuntary captures attention (value-driven attentional capture; VDAC). Recent studies report VDAC even when the reward-associated feature does not define the target (i.e., task-irrelevant). However, these studies did not conduct the test phase without reward, thus the effect may be qualitatively different from those in the previous studies. In the current study, we tested if task-irrelevant features induce VDAC even in the test phase with no reward. We used a flanker task during reward learning to create color-reward associations (training phase), and then tested the effect of color during visual search (test phase). Reward learning with no spatial uncertainty in the flanker task induced VDAC, even when reward signaling color was associated with both target and distractor (Experiments 1 and 2). In Experiment 3, a significant VDAC with a color for all letters indicated that target-distractor discrimination is not necessary for VDAC. Finally, a significant VDAC (Experiment 4) with color rectangular frames around the letters indicated binding reward-associated features to task-relevant letters is not necessary for VDAC. All these effects were obtained in the test phase without reward, thus VDAC in the current study is comparable to previous studies using target-defining features. These findings indicate that task-relevance is not a necessary condition for VDAC from reward-associated features, suggesting that reward-associated learning in VDAC is more indirect.