No reliable effect of task-irrelevant cross-modal statistical regularities on distractor suppression.

Our sensory systems are known to extract and utilize statistical regularities in sensory inputs across space and time for efficient perceptual processing. Past research has shown that participants can utilize statistical regularities of target and distractor stimuli independently within a modality either to enhance the target or to suppress the distractor processing. Utilizing statistical regularities of task-irrelevant stimuli across different modalities also enhances target processing. However, it is not known whether distractor processing can also be suppressed by utilizing statistical regularities of task-irrelevant stimulus of different modalities. In the present study, we investigated whether the spatial (Experiment 1) and non-spatial (Experiment 2) statistical regularities of task-irrelevant auditory stimulus could suppress the salient visual distractor. We used an additional singleton visual search task with two high-probability colour singleton distractor locations. Critically, the spatial location of the high-probability distractor was either predictive (valid trials) or unpredictive (invalid trials) based on the statistical regularities of the task-irrelevant auditory stimulus. The results replicated earlier findings of distractor suppression at high-probability locations compared to the locations where distractors appear with lower probability. However, the results did not show any RT advantage for valid distractor location trials as compared with invalid distractor location trials in both experiments. When tested on whether participants can express awareness of the relationship between specific auditory stimulus and the distractor location, they showed explicit awareness only in Experiment 1. However, an exploratory analysis suggested a possibility of response biases at the awareness testing phase of Experiment 1. Overall, results indicate that irrespective of awareness of the relationship between auditory stimulus and distractor location regularities, there was no reliable influence of task-irrelevant auditory stimulus regularities on distractor suppression.

Spatial distribution of emotional attentional blink under top-down attentional control.

Emotion-induced blindness (EIB) refers to the impaired perception of a neutral target that follows an emotional distractor within the time gap of 100-500 ms. Recent studies on EIB show that EIB is spatially localized. Blink occurs when both target and emotional distractor appear in the same stream but not the opposite. However, the influence of top-down attentional control over the dual-stream EIB remains poorly understood. Examining the role of top-down control in EIB will help understand the impact of attentional control over the spatial distribution of EIB and in understanding the Attentional Blink (AB) and EIB distinction. Hence, in the present study, we used dual-stream and manipulated the attentional control by changing the relevance of the emotional image and asking participants to report both emotional and neutral targets. Our results show a similar level of blink irrespective of the spatial location of the emotional T1, suggesting the role of attentional control on the spatial distribution of EIB and in the AB-EIB distinction. Results have implications for the theoretical understanding of EIB.

Diminished distractor exclusion for magnocellular features near the hand.

The modulated visual pathway (MVP) hypothesis attempts to explain a range of differences observed in the processing of objects in the proximal as compared to the distal region of the hand. However, there has been no account of how 'hand proximity' interacts with task relevance within the MVP framework. In the present study, we used a visual search task to test whether the task relevance of a unique feature (motion in Expt. 1, and color in Expt. 2) influences its processing with respect to the hand. The feature was either relevant (Expt. 1a and 2a) or irrelevant (Expt. 1b and 2b) to the search task. The hand proximity effect was observed only in the experiments in which the unique feature was task irrelevant. However, the effect of hand proximity was overridden when the unique feature was predictive of the target location. We propose that it is difficult to accomplish active distractor rejection of magnocellular features near the hand. Similarly, there is improved active distractor rejection of parvocellular features in the distal region of the hand. Overall, the results suggest that processes involving active distractor rejection may drive the attentional effect of hand proximity.

Challenges to the Modularity Thesis Under the Bayesian Brain Models.

Modularity assumption is central to most theoretical and empirical approaches in cognitive science. The Bayesian Brain (BB) models are a class of neuro-computational models that aim to ground perception, cognition, and action under a single computational principle of prediction-error minimization. It is argued that the proposals of BB models contradict the modular nature of mind as the modularity assumption entails computational separation of individual modules. This review examines how BB models address the assumption of modularity. Empirical evidences of top-down influence on early sensory processes is often cited as a case against the modularity thesis. In the modularity thesis, such top-down effects are attributed to attentional modulation of the output of an early impenetrable stage of sensory processing. The attentional-mediation argument defends the modularity thesis. We analyse this argument using the novel conception of attention in the BB models. We attempt to reconcile classical bottom-up vs. top-down dichotomy of information processing, within the information passing scheme of the BB models. Theoretical considerations and empirical findings associated with BB models that address the modularity assumption is reviewed. Further, we examine the modularity of perceptual and motor systems.

Slower attentional disengagement but faster perceptual processing near the hand.

Many recent studies have reported altered visual processing near the hands. However, there is no definitive agreement about the mechanisms responsible for this effect. One viewpoint is that the effect is predominantly attentional while others argue for the role of pre-attentive perceptual differences in the manifestation of the hand-proximity effect. However, in most of the studies pre-attentional and attentional effects have been conflated. We argue that it is important to dissociate the effect of hand proximity on perception and attention to better theorize and understand how visual processing is altered near the hands. We report two experiments using a visual search task where participants completed a visual search task with their hands either on the monitor or on their lap. When on the monitor, the target could appear near the hand or farther away. In experiment 1, a letter search task showed steeper search slope near the hand suggesting slower attentional disengagement. However, the intercept was smaller in the near hand condition suggesting faster perceptual processing. These results were also replicated in experiment 2 with a conjunction search task with target present and absent conditions and 4 set sizes. The results suggest that there are dissociable effects of hand proximity on perception and attention. Importantly, the pre-attentive advantage of hand proximity does not translate to attentional benefit, but a processing cost. The results of experiment 2 additionally indicate that the steeper slope does not arise from any spatial biases in how search proceeds, but an indicator of slower attentional processing near the hands. The results also suggest that the effect of hand proximity on attention is not spatially graded whereas its effect on perceptuo-motor processes seems to be.

The relationship between action-effect monitoring and attention capture.

Many recent findings suggest that stimuli that are perceived to be the consequence of one's own actions are processed with priority. According to the preactivation account of intentional binding, predicted consequences are preactivated and hence receive a temporal advantage in processing. The implications of the preactivation account are important for theories of attention capture, as temporal advantage often translates to attention capture. Hence, action might modulate attention capture by feature singletons. Experiment 1 showed that a motion onset and color change captured attention only when it was preceded by an action. Experiment 2 showed that the capture occurs only with predictable, but not with unpredictable, consequences of action. Experiment 3 showed that even when half the display changed color at display transition, they were all prioritized. The results suggest that action modulates attentional control.

The role of flicker and abrupt displacement in attention capture by motion onsets.

Sunny and von Mühlenen (Psychonomic Bulletin & Review, 18, 1050-1056, 2011) showed that an onset of motion captured attention only when the motion was jerky (refreshed at 8 or 17 Hz), but not when it was smooth (33 or 100 Hz). However, it remained unclear why the onset of jerky motion captures attention. In the present study, we systematically tested the role of different aspects of jerky motion in capturing attention. Simple flicker without motion did not capture attention in the same way as jerky motion (Exp. 1). An abrupt displacement between 0.26° and 1.05° captured attention, irrespective of whether the stimulus subsequently continued to move smoothly (Exp. 2) or whether it remained stationary (Exps. 3 and 4). A displaced stimulus that was preceded briefly at the new location by a figure-8 placeholder did not capture attention (Exp. 5). These results are explained within a masking account, according to which abrupt onsets and abrupt displacements receive a processing advantage because they escape forward masking by the preceding figure-8 placeholders.

Motion onset does not capture attention when subsequent motion is "smooth".

Previous research on the attentional effects of moving objects has shown that motion per se does not capture attention. However, in later studies it was argued that the onset of motion does capture attention. Here, we show that this motion-onset effect critically depends on motion jerkiness--that is, the rate at which the moving stimulus is refreshed. Experiment 1 used search displays with a static, a motion-onset, and an abrupt-onset stimulus, while systematically varying the refresh rate of the moving stimulus. The results showed that motion onset only captures attention when subsequent motion is jerky (8 and 17 Hz), not when it is smooth (33 and 100 Hz). Experiment 2 replaced motion onset with continuous motion, showing that motion jerkiness does not affect how continuous motion is processed. These findings do not support accounts that assume a special role for motion onset, but they are in line with the more general unique-event account.