A behavioral and eye movement study on inhibitory processing of action memory

Recent evidence highlights the critical role of effective interference inhibition for optimal memory performance, yet its function in action memory remains relatively underexplored. The current study investigated inhibitory processes in action memory during encoding and storage stages. In Experiment 1, 100 participants were divided into high and low cognitive inhibition groups using the Stroop color naming task. They performed either a subject-performed task (SPT) or a verbal task (VT) under varying semantic interference levels to assess the interaction between individual inhibitory abilities and the inhibition processing of action memory during encoding. Results indicated no significant difference in inhibition effects (IF) between high and low inhibition groups in SPT under high semantic interference, while in VT, those with high cognitive inhibition demonstrated significantly greater IF than those with low. Experiment 2, involving 57 participants, employed a point detection task and eye-tracking to explore attentional inhibition mechanisms during action memory storage. Behavioral results showed greater IF for SPT than VT under semantic interference. Eye-tracking revealed higher initial fixation rates and shorter durations for SPT subjects during the early processing stage, and significantly fewer and shorter fixations in the later stage compared to VT subjects. These findings imply stronger inhibitory processing in SPT during both encoding and storage stages under semantic interference, with attentional inhibition of action memories occurring predominantly in the later stage.

Context matters: The interactive effect of introvert-extrovert personality traits and object valence on object-based attention

Previous research has independently investigated the impact of individual personality traits and object valence on different patterns of attentional selection. However, the interactive role of individual personality traits and object valence in different patterns of attentional selection in both same and different emotional contexts remains unclear. To address the above issues, the present research used a variant of the two-rectangle paradigm, preselected individuals as introverts and extroverts, and simultaneously presented two faces with same or different emotions. Accordance to the result, in the same emotional context, personality traits and object valence did not interact to modulate both space-based effect (SBE) and object-based effect (OBE). However, in the different emotional context, personality traits and object valence interacted to modulate OBE. Specifically, for the extroverts, OBE existed no difference among negative, neutral and positive conditions. In contrast, for the introverts, the OBE was larger in the negative condition compared to those in the positive and neutral conditions. This research provides the first evidence suggesting that object-based attention can be impacted by the interaction between individual characteristics and object properties, and further proposes a preliminary framework called "context-dependent attentional selection hypothesis."

Visual search training benefits from the integrative effect of enhanced covert attention and optimized overt eye movements

Training serves as an effective approach to improve visual search performance when the target does not automatically pop out from the distractors. In the present study, we trained participants on a conjunction visual search task and examined the training effects in behavior and eye movement. The results of Experiments 1 to 4 showed that training improved behavioral performance and reduced the number of saccades and overall scanning time. Training also increased the search initiation time before the first saccade and the proportion of trials in which the participants correctly identified the target without any saccade, but these effects were modulated by stimulus’ parameters. In Experiment 5, we simultaneously recorded eye movements and electroencephalography signals and the results revealed significant N2 posterior contralateral (N2pc) components after the stimulus onset (i.e., stimulus-locked) and before the first saccade (i.e., saccade-locked) when the search target was the trained one. These N2pc components can be considered as the neural signatures for the enhanced covert attention to the trained target. Together with the training-induced increase in functional visual field, these mechanisms could support the beneficial effects of increased search initiation time and reduced number of saccades. These findings suggest that visual search training enhanced covert attention to target and optimized overt eye movements to facilitate search performance.

Reduction of temporal uncertainty facilitates stimulus-driven processes in spatial selection

Previous studies have shown that the reduction of temporal uncertainty facilitates target selection in visual search. We investigated whether this beneficial effect is caused by an effect on stimulus-driven processes or on goal-driven processes in spatial selection. To discriminate between these processes, we employed a visual search task in which participants searched for a shape target while ignoring a color singleton distractor. As an index of stimulus-driven processes, we measured the N2pc evoked by the singleton distractor (N_D). As indices of goal-driven processes, we measured the N2pc evoked by the target (N_T) and the distractor positivity (P_D) evoked by the singleton distractor, respectively. We observed that reducing temporal uncertainty modulated the amplitude of N_D and the onset latency of the N_T, but did not modulate the amplitude of the P_D. These results are consistent with the view that a reduction of temporal uncertainty influences non-selective, stimulus-driven processes in spatial selection.

Shifting Attention in Feature Space: Fast Facilitation of the To-Be-Attended Feature Is Followed by Slow Inhibition of the To-Be-Ignored Feature

In an explorative study, we investigated the time course of attentional selection shifts in feature-based attention in early visual cortex by means of steady-state visual evoked potentials (SSVEPs). To this end, we presented four flickering random dot kinematograms with red/blue, horizontal/vertical bars, respectively. Given the oscillatory nature of SSVEPs, we were able to investigate neural temporal dynamics of facilitation and inhibition/suppression when participants shifted attention either within (i.e., color to color) or between feature dimensions (i.e., color to orientation). Extending a previous study of our laboratory [Müller, M. M., Trautmann, M., & Keitel, C. Early visual cortex dynamics during top-down modulated shifts of feature-selective attention. Journal of Cognitive Neuroscience, 28, 643-655, 2016] to a full factorial design, we replicated a critical finding of our previous study: Facilitation of color was quickest, regardless of the origin of the shift (from color or orientation). Furthermore, facilitation of the newly to-be-attended and inhibition/suppression of the then to-be-ignored feature is not a time-invariant process that occurs instantaneously, but a biphasic one with longer time delays between the two processes. Interestingly, inhibition/suppression of the to-be-ignored feature after the shifting cue had a much longer latency with between- compared to within-dimensional shifts (by about 130-150 msec). The exploratory nature of our study is reasoned by two limiting factors: (a) Identical to our precursor study, we found no attentional SSVEP amplitude time course modulation for orientation, and (b) the signal-to-noise ratio for single trials was too poor to allow for reliable statistical testing of the latencies that were obtained with running t tests of averaged data.

Towards Interactive Search: Investigating Visual Search in a Novel Real-World Paradigm

An overwhelming majority of studies on visual search and selective attention were conducted using computer screens. There are arguably shortcomings in transferring knowledge from computer-based studies to real-world search behavior as findings are based on viewing static pictures on computer screens. This does not go well with the dynamic and interactive nature of vision in the real world. It is crucial to take visual search research to the real world in order to study everyday visual search processes. The aim of the present study was to develop an interactive search paradigm that can serve as a "bridge" between classical computerized search and everyday interactive search. We based our search paradigm on simple LEGO® bricks arranged on tabletop trays to ensure comparability with classical computerized visual search studies while providing room for easily increasing the complexity of the search environment. We found that targets were grasped slower when there were more distractors (Experiment 1) and there were sizable differences between various search conditions (Experiment 2), largely in line with classical visual search research and revealing similarities to research in natural scenes. Therefore, our paradigm can be seen as a valuable asset complementing visual search research in an environment between computerized search and everyday search.

Flexible weighting of target features based on distractor context

Models of attention posit that attentional priority is established by summing the saliency and relevancy signals from feature-selective maps. The dimension-weighting account further hypothesizes that information from each feature-selective map is weighted based on expectations of how informative each dimension will be. In the current studies, we investigated the question of whether attentional biases to the features of a conjunction target (color and orientation) differ when one dimension is expected to be more diagnostic of the target. In a series of color-orientation conjunction search tasks, observers saw an exact cue for the upcoming target, while the probability of distractors sharing a target feature in each dimension was manipulated. In one context, distractors were more likely to share the target color, and in another, distractors were more likely to share the target orientation. The results indicated that despite an overall bias toward color, attentional priority to each target feature was flexibly adjusted according to distractor context: RT and accuracy performance was better when the diagnostic feature was expected than unexpected. This occurred both when the distractor context was learned implicitly and explicitly. These results suggest that feature-based enhancement can occur selectively for the dimension expected to be most informative in distinguishing the target from distractors.

Studying the dynamics of visual search behavior using RT hazard and micro-level speed-accuracy tradeoff functions: A role for recurrent object recognition and cognitive control processes

Thanks to the work of Anne Treisman and many others, the visual search paradigm has become one of the most popular paradigms in the study of visual attention. However, statistics like mean correct response time (RT) and percent error do not usually suffice to decide between the different search models that have been developed. Recently, to move beyond mean performance measures in visual search, RT histograms have been plotted, theoretical waiting time distributions have been fitted, and whole RT and error distributions have been simulated. Here we promote and illustrate the general application of discrete-time hazard analysis to response times, and of micro-level speed-accuracy tradeoff analysis to timed response accuracies. An exploratory analysis of published benchmark search data from feature, conjunction, and spatial configuration search tasks reveals new features of visual search behavior, such as a relatively flat hazard function in the right tail of the RT distributions for all tasks, a clear effect of set size on the shape of the RT distribution for the feature search task, and individual differences in the presence of a systematic pattern of early errors. Our findings suggest that the temporal dynamics of visual search behavior results from a decision process that is temporally modulated by concurrently active recurrent object recognition, learning, and cognitive control processes, next to attentional selection processes.

Visual working memory impairments for single items following medial temporal lobe damage

A growing body of research indicates that the medial temporal lobe (MTL) is essential not only for long-term episodic memory but also for visual working memory (VWM). In particular, recent work has shown that the MTL is especially important for VWM when complex, high-resolution binding is required. However, all of these studies tested VWM for multiple items which invites the possibility that working memory capacity was exceeded and patient impairments instead reflected deficits in long-term memory. Thus, the precise conditions under which the MTL is critical for VWM and the type of working memory processes that are affected by MTL damage are not yet clear. To address these issues, we examined the effects of MTL damage on VWM for a single item (i.e., a square that contained color, location, and orientation information) using confidence-based receiver operating characteristic methods to assess VWM discriminability and to separate perceiving- and sensing-based memory judgments. This approach was motivated by dual-process theories of cognition that posit distinct subprocesses underlie performance across perception, working memory, and long-term memory. The results indicated that MTL patients were significantly impaired in VWM for a single item. Interestingly, the patients were not impaired at making accurate high-confidence judgments that a change had occurred (i.e., perceiving), rather they were impaired at making low-confidence judgments that they sensed whether or not there had been a change in the absence of identifying the exact change. These results demonstrate that the MTL is critical in supporting working memory even for a single item, and that it contributes selectively to sensing-based discriminations.

The Hyperfocusing Hypothesis: A New Account of Cognitive Dysfunction in Schizophrenia

Impairments in basic cognitive processes such as attention and working memory are commonly observed in people with schizophrenia and are predictive of long-term outcome. In this review, we describe a new theory-the hyperfocusing hypothesis-which provides a unified account of many aspects of impaired cognition in schizophrenia. This hypothesis proposes that schizophrenia involves an abnormally narrow but intense focusing of processing resources. This hyperfocusing impairs the ability of people with schizophrenia to distribute attention among multiple locations, decreases the number of representations that can simultaneously be maintained in working memory, and causes attention to be abnormally captured by irrelevant inputs that share features with active representations. Evidence supporting the hyperfocusing hypothesis comes from a variety of laboratory tasks and from both behavioral and electrophysiological measures of processing. In many of these tasks, people with schizophrenia exhibit supranormal effects of task manipulations, which cannot be explained by a generalized cognitive deficit or by nonspecific factors such as reduced motivation or poor task comprehension. In addition, the degree of hyperfocusing in these tasks is often correlated with the degree of impairment in measures of broad cognitive function, which are known to be related to long-term outcome. Thus, the mechanisms underlying hyperfocusing may be a good target for new treatments targeting cognitive deficits in schizophrenia.

Electrophysiological correlates of active suppression and attentional selection in preview visual search

Advance preview of a subset of distractor objects improves the efficiency of visual search performance, but the causes and mechanisms of such preview benefits remain unclear. Here, we employed event-related potential (ERP) markers of the selective processing of preview displays and full search displays in lateralised preview search tasks where only one side of the search displays was task-relevant. Preview displays elicited a sustained positivity contralateral to the relevant side (P_D component), indicative of the active suppression of distractor objects on this side. Lateralised ERP components to full search displays revealed qualitative differences between attentional selection processes on preview as compared to no-preview trials. When search displays were preceded by preview displays, attention was directly allocated to target objects, while distractors remained unattended. When all search display objects were presented simultaneously (no-preview), attention was directed non-selectively to objects on the task-relevant side, even when no target was present. These results suggest that behavioural preview effects in visual search can be accounted for by the inhibition of previewed distractors, and the subsequent rapid attentional selection of target objects on preview trials.