Continuous action with a neurobiologically inspired computational approach reveals the dynamics of selection history.

Everyday perception-action interaction often requires selection of a single goal from multiple possibilities. According to a recent framework of attentional control, object selection is guided not only by the well-established factors of perceptual salience and current goals but also by selection history. Yet, underlying mechanisms linking selection history and visually-guided actions are poorly understood. To examine such interplay and disentangle the impact of target and distractor history on action selection, we employed a priming-of-popout (PoP) paradigm combined with continuous tracking of reaching movements and computational modeling. Participants reached an odd-colored target among homogeneous distractors while we systematically manipulated the sequence of target and distractor colors from one trial to the next. We observed that current reach movements were significantly influenced by the interaction between attraction by the prior target feature and repulsion by the prior distractor feature. With principal component regression, we found that inhibition led by prior distractors influenced reach target selection earlier than facilitation led by the prior target. In parallel, our newly developed computational model validated that current reach target selection can be explained best by the mechanism postulating the preceded impact of previous distractors followed by a previous target. Such converging empirical and computational evidence suggests that the prior selection history triggers a dynamic interplay between target facilitation and distractor inhibition to guide goal-directed action successfully. This, in turn, highlights the necessity of an explicitly integrated approach to determine how visual attentional selection links with adaptive actions in a complex environment.

Target detection and discrimination in pop-out visual search with two targets.

To successfully interact with objects in complex and crowded environments, we often perform visual search to detect or identify a relevant target (or targets) among distractors. Previous studies have reported a redundancy gain when two targets instead of one are presented in a simple target detection task. However, research is scant about the role of multiple targets in target discrimination tasks, especially in the context of visual search. Here, we address this question and investigate its underlying mechanisms in a pop-out search paradigm. In Experiment 1, we directly compared visual search performance for one or two targets for detection or discrimination tasks. We found that two targets led to a redundancy gain for detection, whereas it led to a redundancy cost for discrimination. To understand the basis for the redundancy cost observed in discrimination tasks for multiple targets, we further investigated the role of perceptual grouping (Experiment 2) and stimulus-response feature compatibility (Experiment 3). We determined that the strength of perceptual grouping among homogenous distractors was attenuated when two targets were present compared with one. We also found that response compatibility between two targets contributed more to the redundancy cost compared with perceptual compatibility. Taken together, our results show how pop-out search involving two targets is modulated by the level of feature processing, perceptual grouping, and compatibility of perceptual and response features.

Group congruent labelling leads to subjective expansion of time.

Given top-down effects on perception, we examined the effect of group identity on time perception. We investigated whether the duration of an ambiguous sound clip is processed differently as a function of group congruent or incongruent source attribution. Group congruent (in-group) and incongruent (out-group) context was created by attributing the source of an identical ambiguous sound clip to Hindu or Muslim festivals. Participants from both the religious groups (Hindus and Muslims) prospectively listened to a 20 s long ambiguous sound clip and reproduced its duration (experiment 1a). Both groups reproduced significantly longer durations when the sound clip was associated with the group congruent compared to the group incongruent festival contexts. The two groups did not differ significantly in reproduced duration when the sound attributed to a non-religious common (busy city street) context (experiment 1b). With multiple durations (1, 5, 10 and 20 s), longer durations were reproduced for group congruent labelling at objectively longer durations (experiment 2). According to the internal clock model of time perception, the significant slope effect indicated that the group congruent context influences temporal experience through changes in pacemaker frequency. We argue that the duration appearing relevant to one's own group is processed differently possibly owing to differences in attentional deployment, which influences the pacemaker frequency.

Self-associated stimuli produce stronger intentional binding.

Self-generated actions are important for survival; they influence perception, especially the subjective time between the action and its outcome, known as intentional binding (IB). Whereas most studies on IB have examined the role of action being associated with the self or not, the role of the outcome being associated with the self or not has received less attention. The major models or mechanisms proposed to explain IB do not explicitly discuss the role of self-association without confounding it with intentionality, causality, and prediction. In this study for the 1st time, we used the self-related processing paradigm to investigate the importance of self-association in IB and the potential importance of postdictive mechanisms in self-associated IB. We used a shape-label matching task to associate different identities like self, friend, and stranger with different geometrical shapes like circle, square, and triangle. After the shape-label matching task, participants performed an IB task, in which they estimated the perceived magnitude of the duration between the action and the ensuing outcome. All the outcomes in this task were unpredictable and were not causally related to any particular action. Results revealed that participants reported the perceived interval between their action and the self-associated outcome to be shorter (i.e., stronger IB) compared to a friend- or stranger-associated outcome, demonstrating that mere labeling of a neutral geometrical shape with self leads to stronger IB. The results point to a potentially important role of postdictive mechanisms in IB and agency associated with self-related processing, which is independent of causality and prediction. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Intended outcome expands in time.

Intentional agents desire specific outcomes and perform actions to obtain those outcomes. However, whether getting such desired (intended) outcomes change our subjective experience of the duration of that outcome is unknown. Using a temporal bisection task, we investigated the changes in temporal perception of the outcome as a function of whether it was intended or not. Before each trial, participants intended to see one of two possible outcomes but received the intended outcome only in half of the trials. Results showed that intended outcomes were perceived as longer than unintended outcomes. Interestingly, this temporal expansion was present only when the intended outcome appeared after short action-outcome delays (250 ms-Exp 1 and 500 ms-Exp 2), but not when it appeared after long action-outcome delay (1000 ms-Exp 3). The effect was absent when participants did not intend and performed instruction-based action (Exp 4). Finally, Exp 5 (verbal estimation task) revealed that intention induced temporal expansion occurs via altering the gating or switch mechanism and not the pacemaker speed. Results are explained based on intention-induced pre-activation resulting in extended temporal experience. Our study not only suggests inclusion of intention as a potential factor influencing time perception but also indicates a close link between intentional binding and the intention induced temporal expansion of its outcome.