Massimo Turatto

Color singleton distractors’ interference is known to be modulated by rejection mechanisms based on the distractors’ probability of occurrence at different locations. Here, to further address color-singleton distractor rejection, we used a modified version of the additional-singleton paradigm, where four consecutive displays were presented in rapid succession on each trial. In Experiment 1 the irrelevant singleton was either presented in the last display (single location, 40% probability) or repeated in all four displays (repeated location, 10% probability), with the two conditions appearing at separate locations. Contrary to common observations, we found that capture was much more attenuated at the repeated location, despite the lower distractor probability. Furthermore, we found no signs of target-processing impairment at the repeated location where capture was basically eliminated, whereas capture was present at the single location. In Experiment 2, where both locations had repeated distractors, we found target-processing impairment only at the location with the highest distractor probability (40%). Experiment 3 indicated that suppression, regardless of any within-trial distractor repetitions, becomes evident only when the distractor probability is high enough (35%). Experiment 4 replicated the main findings in a single experiment, within the same group of participants. The results suggest the possible existence of distinct rejection mechanisms based on within-trial and across-trials distractor repetitions. While suppression is probably involved in the across-trials rejection mechanism, we propose that the one operating on a shorter within-trial time scale is likely controlled solely by a distractor-expectation or distractor-prediction error mechanism.

Statistical learning-based filtering mechanisms reduce attentional capture more for frequent than for infrequent distractors, a phenomenon known as the “distractor frequency effect”. In the field of object-based attention, this effect has been studied with real-world object distractors, which engage both perceptual and semantic processing of distracting information. Whether similar mechanisms are also engaged by meaningless distractors remains unknown. Within a template-for-rejection framework of filtering mechanisms, we hypothesized that perceptual grouping of distracting visual input into coherent units is the minimal sufficient condition for these mechanisms to operate. In Experiment 1, Gabor patches were presented with superimposed distractors, consisting of either outlined meaningless distracting shapes or scattered-dot displays, which appeared within a block of trials at either high or low frequency. Shapes produced greater interference in Gabor orientation discrimination than scattered dots, despite the two being equivalent in terms of sensory energy impinging on the retina, indicating that additional processing was required to group the elements into shapes. Furthermore, less frequent shape distractors caused greater interference than more frequent ones. This distractor frequency effect was absent for scattered-dot displays but re-emerged in Experiment 2 where the scattered dots were grouped by proximity into multi-regional patterns, indicating that perceptual grouping was critical for this effect to occur. Experiment 3 demonstrated that the frequency effect stems from statistical learning rather than perceptual learning of the compound target-distractor pattern. We propose that Gestalt grouping may facilitate the formation of distractor templates, which are then used to filter task-irrelevant information, thereby reducing object-based distractor interference.

Color singleton distractors interference is modulated by rejection mechanisms that take into account the distractors rate of occurrence at different locations. Here, to further address color-singleton distractor rejection, we used a modified version of the additional-singleton paradigm, where each trial consisted of four consecutive displays presented in rapid succession. In Experiment 1 the irrelevant singleton was either presented in the last display (single condition, 40% rate) or repeated in all four displays (repeated condition, 10% rate), with the two conditions appearing at separate locations. Contrary to common observations, we found that capture was much more attenuated at the repeated location, despite the lower distractor rate. Furthermore, we found no signs of target processing impairment at the location where capture was basically eliminated, whereas it was present where capture was robust. In Experiment 2, where both locations had repeated distractors, we found target processing impairment only at the location with the highest rate (40%); Experiment 3, indicated that suppression, regardless of any within trial distractor repetitions, becomes evident when the distractor rate is high enough (35%). Experiment 4 replicated these separate previous findings in a single experiment, within the same group of participants. The results suggest the possible existence of rejection mechanisms working on distinct time scales, based on within trial and across trials distractor repetitions. While the across trials mechanism seems to rely on a durable form of suppression to control capture, the within trial one might rely on short-term distractor expectation, or involve a volatile form of suppression.

Decrement of attentional capture elicited by visual onset distractors, consistent with habituation, has been extensively characterized over the past several years. However, the type of spatial frame of reference according to which such decrement occurs in the brain remains unknown. Here, four related experiments are reported to shed light on this issue. Observers were asked to discriminate the orientation of a titled line while ignoring a salient but task-irrelevant visual onset that occurred on some trials. The experiments all involved an initial habituation phase, during which capture elicited by the onset distractor progressively decreased, as in prior studies. Importantly, in all experiments, the location of the target and the distractor remained fixed during this phase. After habituation was established, in a final test phase of the various experiments, the spatial arrangement of the target and the distractor was changed to test for the relative contribution to habituation of retinotopic, spatiotopic, and configuration-dependent visual representations. Experiment 1 indicated that spatiotopic representations contribute little, if at all, to the observed decrement in attentional capture. The results from Experiment 2 were compatible with the notion that such capture reduction occurs in either retinotopic- or configuration-specific representations. However, Experiment 3 ruled out the contribution of retinotopic representations, leaving configuration-specific representation as the sole viable interpretation. This conclusion was confirmed by the results of Experiments 4 and 5. In conclusion, visual onset distractors appear to be rejected at a level of the visual hierarchy where visual events are encoded in a configuration-specific or context-dependent manner. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Can signs of intentional behavior be traced in an insect larva, traditionally thought to be driven only by mere reflexes? We trained Tenebrio molitor coleoptera larvae in a uniform Y-maze to prefer one target branch to get access to food, observing their ability to learn and retain access to the reward-associated side for up to 24 h. During reward devaluation, the reward food (experimental group) and a different food (control group) were paired with an aversive stimulus in a new environment. When tested again in the Y-maze, mealworms of the experimental group significantly reduced their visits to the target branch, whereas mealworms of the control group did not. Importantly, we found that the larvae did not have to experience the unpleasant consequences directly in the target branch to halt their behavior, as the exposure to the aversive taste occurred in a separate unfamiliar context. This is evidence that the mealworms formed a mental representation of action-consequence relationships, demonstrating flexible control of their actions to achieve desired outcomes at an early stage of their development.

Summary: Habituation mechanisms play a pivotal role in enabling organisms to filter out irrelevant stimuli and concentrate on essential ones. Through repeated exposure, the brain learns to disregard stimuli that are irrelevant, effectively ceasing to respond to potentially distracting input. Previous studies have demonstrated that the orienting response to visual distractors disrupting visual detection tasks habituates as tasks progress and distractors are encountered repeatedly, as their initial interference diminishes. Theoretical models posit that this reduction is contingent upon the establishment of an internal representation of external stimuli. Moreover, further studies have indicated that habituation can be context- specific, suggesting that the mechanisms involved incorporate information about features of irrelevant stimuli that extend beyond their discrete characteristics. In this contribution, we further delved into the question of whether the context in which habituation occurs retains a general habituative capacity when a new, to-be-ignored stimulus is introduced. We discuss evidence indicating that the context in which habituation has already taken place facilitates the habituation process for a new stimulus. This suggests that it becomes easier to ignore new stimuli in contexts where we have already learned to disregard other stimuli, underscoring the intricate interplay between habituation, context, and attentional processes.

Hemispheric specialization influences stimulus processing and behavioural control, affecting responses to relevant stimuli. However, most sensory input is irrelevant and must be filtered out to prevent interference with task-relevant behaviour, a process known as habituation. Despite habituation's vital role, little is known about hemispheric specialization for this brain function. We conducted an experiment with domestic chicks, an elite animal model to study lateralization. They were exposed to distracting visual stimuli while feeding when using binocular or monocular vision. Switching the viewing eye after habituation, we examined if habituation was confined to the stimulated hemisphere or shared across hemispheres. We found that both hemispheres learned equally to ignore distracting stimuli. However, embryonic light stimulation, influencing hemispheric specialization, revealed an asymmetry in interhemispheric transfer of the irrelevant information discarded via habituation. Unstimulated chicks exhibited a directional bias, with the right hemisphere failing to transfer distracting stimulus information to the left hemisphere, while transfer from left to right was possible. Nevertheless, embryonic light stimulation counteracted this asymmetry, enhancing communication from the right to the left hemisphere and reducing the pre-existing imbalance. This sharing extends beyond hemisphere-specific functions and encompasses a broader representation of irrelevant events.

Habituation represents a well-established form of learning in various neuroscience domains. However, cognitive psychologists working in the field of visual attention have largely overlooked this phenomenon. In this regard, I would like to argue that the reduction in attentional capture observed with repetitive salient distractors, and specifically abrupt visual onsets, could be attributed to habituation. Three classic models of habituation, independently devised by Sokolov, Wagner, and by Thompson, will be presented and discussed in relation to the capture of attention. Of particular interest is the fact that Sokolov's model is governed by a prediction-error minimization principle, where a stimulus attracts attention to the extent that it violates the expected sensory input, which is anticipated on the basis of the previous history of stimulation. Hence, at least in humans, habituation is governed by high-order cognitive processes, and should not be confounded with peripheral sensory adaptation or fatigue. Furthermore, the cognitive nature of habituation is also attested by the fact that visual distractor filtering is context-specific. In conclusion, as already suggested by others, I believe that researchers working in the field of attention should give more consideration to the notion of habituation, especially with regard to the control of stimulus-driven capture. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Habituation to onset distractors has been shown to be stronger the higher the distractor probability. However, since in previous studies distractor probability covaried with distractor numerosity, it was unclear whether habituation was controlled by a mechanism that relies on distractor expectation (Sokolov, 1963), or by a mechanism that is merely driven by the number of stimulations delivered to the nervous system (Groves & Thompson, 1970). To address this issue, we manipulated the probability of distractor occurrence at a fixed location, without varying the number of distractors being presented. The results of Experiment 1 clearly favored the Sokolov model of habituation, showing that habituation of capture is controlled by the level of distractor expectation for the same distractors number. Experiment 2 excluded that the pattern of habituation was determined by the difference in the temporal frequency of the distractor between higher and lower distractor rates. Furthermore, the results of Experiment 3 suggested that the amount of habituation of capture is mainly controlled by the local rather than by the global rate of the onset distractor occurrence, thus indicating that habituation of capture is largely spatially specific. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

An increasing bulk of evidence shows that through different mechanisms, experienced-based or voluntary, reactive or proactive, human beings can attenuate t