Stimulus-driven Control Research Articles

Separate and overlapping mechanisms of statistical regularities and salience processing in the occipital cortex and dorsal attention network.

Attention selects behaviorally relevant inputs for in-depth processing. Beside the role of traditional signals related to goal-directed and stimulus-driven control, a debate exists regarding the mechanisms governing the effect of statistical regularities on attentional selection, and how these are integrated with other control signals. Using a visuo-spatial search task under fMRI, we tested the joint effects of statistical regularities and stimulus-driven salience. We found that both types of signals modulated occipital activity in a spatially specific manner. Salience acted primarily by reducing the attention bias towards the target location when associated with irrelevant distractors, while statistical regularities reduced this attention bias when the target was presented at a low probability location, particularly at the lower levels of the visual hierarchy. In addition, we found that both statistical regularities and salience activated the dorsal frontoparietal network. Additional exploratory analyses of functional connectivity revealed that only statistical regularities modulated the inter-regional coupling between the posterior parietal cortex and the occipital cortex. These results show that statistical regularities and salience signals are both spatially represented at the occipital level, but that their integration into attentional processing priorities relies on dissociable brain mechanisms.

Insula lesions reduce stimulus-driven control of behavior during odor-guided decision-making and autoshaping

The insula has become a significant brain region in the study of both normal and impaired behavior and decision-making and has emerged as an important contributor to drug addiction. Consistent with this literature, in a previous study, we found that neural signals in rat insula encode anticipation and contextual global reward value during performance of an odor-guided delay/size choice task, and that these signals are disrupted by prior cocaine self-administration. Still, it is unknown if insula is critical for performance of this task under normal circumstances. Here, we sought to elucidate the functional role of these signals by lesioning the same region of anterior insula we previously recorded from. In addition to examining behavior during decision-making, we characterized behavior during autoshaping to further assess insula’s role in behavior. We found insula damage resulted in reduced accuracy and faster reaction times, without affecting rats’ choice of high-value reward, and that insula lesions reduced sign-tracking behavior. These results suggest that insula contributes to our odor-guided delay/size choice task via mechanisms that impact the control that environmental stimuli have on behavior.

The transfer of location-based control requires location-based conflict

It is well supported that stimulus-driven control of attention varies depending on the degree of conflict previously encountered in a given location. Previous research has further shown that control settings established in conflict-biased locations can transfer to nearby unbiased items. However, these spatial transfer effects have only been shown using incompatible flanking arrows (i.e., stimuli that trigger spatial information) to elicit conflict in a flanker task. Here we examine the generalizability of transfer of control by examining if it can occur across a range of tasks. We employ a classic Stroop task (Experiment 1), a spatially segregated Stroop task (Experiment 2), and a spatial Stroop task (Experiment 3). Location-specific proportion compatibility effects were observed in all variations of the Stroop task tested; however, transfer to unbiased items occurred only in the spatial Stroop task in Experiment 3. This suggests that the transfer of cognitive control settings within spatial categories may occur only in tasks where the source of conflict is spatial, as arises in tasks with arrow and direction word stimuli.

Effects of Coping-Related Traits and Psychophysiological Stress Responses on Police Recruits' Shooting Behavior in Reality-Based Scenarios.

Police officers are often required to perform under high-stress circumstances, in which optimal task performance is crucial for their and the bystanders’ physical integrity. However, stress responses, particularly anxiety and increased cortisol levels, shift attention from goal-directed to stimulus-driven control, leaving police officers with poor shooting performance under stress. Cardiac vagal activity and coping-related traits (i.e., self-control, sensation seeking) might help individuals to maintain performance under stress. So far, only few studies have integrated coping-related traits, psychophysiological stress markers and occupationally meaningful measures of behavior to investigate police officers’ work performance under stress. Therefore, the present study investigated 19 police recruits (Mage = 22.84, SD = 3.30) undergoing a reality-based shooting scenario in two experimental conditions in a within-design: low stress (LS) against a non-threatening mannequin, and high stress (HS), involving physical threat by an opponent. Psychological (i.e., anxiety, mental effort) and physiological stress responses (i.e., salivary cortisol, alpha-amylase, cardiac vagal activity) as well as shooting accuracy were repeatedly assessed. It was hypothesized that under stress, police recruits would demonstrate elevated psychophysiological stress responses and impaired shooting performance. Elevated psychophysiological stress responses would negatively influence shooting performance, whereas self-control, sensation seeking and cardiac vagal activity would positively influence shooting performance. While recruits reported significantly higher anxiety and mental effort in the HS scenario, both scenarios elicited comparable physiological responses. Overall, shooting accuracy was low and did not significantly decrease in the HS scenario. Shooting performance was predicted by self-control in the LS scenario and by post-task cardiac vagal activity in the HS scenario. While increased anxiety hints at a successful stress manipulation, physiological responses suggest similar stress levels for both scenarios, diminishing potential behavioral differences between the scenarios. Performance efficiency decreased under stress, as indicated by increasing mental effort. Findings on self-control suggest that suppressing negative stress responses might lead to impaired goal-directed attention, resulting in performance decrements. For police research and training, high-realism scenarios afford an opportunity to investigate and experience psychophysiological stress responses.

Task context load induces reactive cognitive control: An fMRI study on cortical and brain stem activity

Cognitive control is a highly dynamic process that relies on flexible engagement of prefrontal areas and of neuromodulatory systems in order to adapt to changing demands. A range of internal and external factors come into play when individuals engage in a task requiring cognitive control. Here we investigated whether increased working memory (WM) demands would induce a flexible change in cognitive control mode in young healthy individuals. We developed a novel variant of the well-known AX–continuous performance task (AX-CPT). We manipulated the cognitive demands of maintaining task-relevant contextual information and studied the impact of this manipulation on behavior and brain activity. We expected that low WM load would allow for a more effortful, proactive strategy, while high WM load would induce a strategy of less effortful, stimulus-driven reactive control. In line with our hypothesis, a web-based experiment revealed that increased load was associated with more reactive behavioral responses, and this finding was independently replicated in behavioral data acquired in the MRI scanner. The results from brain activity showed that the right dorsolateral prefrontal cortex was activated by cues in the proactive mode and by probes in the reactive mode. The analysis of task-induced brain stem activity indicated that both the dopaminergic and noradrenergic systems are involved in updating context representations, and that, respectively, these systems mediate a gating signal to the control network and are involved in the dynamic regulation of task engagement.

When stimulus-driven control settings compete: On the dominance of categories as cues for control.

Stimulus-driven or reactive control refers to the modulation of attention poststimulus onset via retrieval of learned control settings associated with task stimuli. The present study asked which stimulus-driven control setting "wins" the competition when more than 1 is available to guide attention. Utilizing an item-specific proportion congruence manipulation in a picture-word Stroop task, 7 experiments examined competition between item-level and category-level control settings. In Experiment 1, category-level control dominated as evidenced by transfer of control to unique 50% congruent items (exemplars) from biased (33% or 67% congruent) animal categories. In Experiment 2, the dominance persisted-transfer was observed even for inconsistent transfer items (e.g., 83% congruent bird from a 33% congruent bird category). Recategorization of the exemplars prior to the Stroop task (Experiment 3a) successfully shifted the dominance to item-level control as did changing the Stroop task goal (Experiment 4a); however, exposure to the exemplars (Experiment 3b) and individuation training prior to the Stroop task did not (Experiments 3c and 4b). These novel findings suggest category-level control dominates in guiding attention poststimulus onset, but this dominance is dependent on contextual features (i.e., mutable). We propose a salience account of dominance and discuss implications for item-based computational models. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Attentional control transfers beyond the reference frame.

Much research has shown that humans can allocate attentional control differentially to multiple locations based on the amount of conflict historically associated with a given location. Additionally, once established, these control settings can transfer to nearby locations that themselves have no conflict bias. Here we examined if these control settings also extend to nearbylocations that are presented outside of the original frame of reference of biased stimuli. During training, participants first responded to biased flanker stimuli that were likely high conflict in one location and low conflict in another location. Then they were exposed to two sets of unbiased stimuli presented in novel transferlocations outside of the established reference frame of biased stimuli. Across three experiments, attentional control settings transferred beyond the reference frame including when there was a visual border (Experiment 2) or meaningful categorical distinction (Experiment 3) delineating training and transferlocations. These novel findings further support the idea that stimulus-driven attention control can be flexibly allocated, perhaps in a categorical manner.

Supplemental Material for When Stimulus-Driven Control Settings Compete: On the Dominance of Categories as Cues for Control

Supplemental Material for When Stimulus-Driven Control Settings Compete: On the Dominance of Categories as Cues for Control

Target-nontarget similarity decreases search efficiency and increases stimulus-driven control in visual search.

Some points of criticism against the idea that attentional selection is controlled by bottom-up processing were dispelled by the attentional window account. The attentional window account claims that saliency computations during visual search are only performed for stimuli inside the attentional window. Therefore, a small attentional window may avoid attentional capture by salient distractors because it is likely that the salient distractor is located outside the window. In contrast, a large attentional window increases the chances of attentional capture by a salient distractor. Large and small attentional windows have been associated with efficient (parallel) and inefficient (serial) search, respectively. We compared the effect of a salient color singleton on visual search for a shape singleton during efficient and inefficient search. To vary search efficiency, the nontarget shapes were either similar or dissimilar with respect to the shape singleton. We found that interference from the color singleton was larger with inefficient than efficient search, which contradicts the attentional window account. While inconsistent with the attentional window account, our results are predicted by computational models of visual search. Because of target-nontarget similarity, the target was less salient with inefficient than efficient search. Consequently, the relative saliency of the color distractor was higher with inefficient than with efficient search. Accordingly, stronger attentional capture resulted. Overall, the present results show that bottom-up control by stimulus saliency is stronger when search is difficult, which is inconsistent with the attentional window account.

Stimulus-driven Control of Attention : Evidence from Visual Search for Moving Target Among Static Nontargets

Stimulus-driven Control of Attention : Evidence from Visual Search for Moving Target Among Static Nontargets

Competition between Visual Events Modulates the Influence of Salience during Free-Viewing of Naturalistic Videos.

In daily life the brain is exposed to a large amount of external signals that compete for processing resources. The attentional system can select relevant information based on many possible combinations of goal-directed and stimulus-driven control signals. Here, we investigate the behavioral and physiological effects of competition between distinctive visual events during free-viewing of naturalistic videos. Nineteen healthy subjects underwent functional magnetic resonance imaging (fMRI) while viewing short video-clips of everyday life situations, without any explicit goal-directed task. Each video contained either a single semantically-relevant event on the left or right side (Lat-trials), or multiple distinctive events in both hemifields (Multi-trials). For each video, we computed a salience index to quantify the lateralization bias due to stimulus-driven signals, and a gaze index (based on eye-tracking data) to quantify the efficacy of the stimuli in capturing attention to either side. Behaviorally, our results showed that stimulus-driven salience influenced spatial orienting only in presence of multiple competing events (Multi-trials). fMRI results showed that the processing of competing events engaged the ventral attention network, including the right temporoparietal junction (R TPJ) and the right inferior frontal cortex. Salience was found to modulate activity in the visual cortex, but only in the presence of competing events; while the orienting efficacy of Multi-trials affected activity in both the visual cortex and posterior parietal cortex (PPC). We conclude that in presence of multiple competing events, the ventral attention system detects semantically-relevant events, while regions of the dorsal system make use of saliency signals to select relevant locations and guide spatial orienting.

Rewards shape attentional search modes

Visual attention can be configured for specific stimulus features (feature search mode) or it can be non-specifically set for salient pop-outs (singleton detection mode). Additionally, monetary rewards have been shown to bias attention toward specific features, but it is unknown whether secondary reinforcers (images of US$) can shape global attention via search modes. In a between-group study, we trained participants to value one search mode over the other. In a testing phase, a salient distractor captured the attention of the value-singleton group; however, the value feature group was completely unaffected. This suggests that rewards automatically bias global attention mechanisms and potentially mediate the handoff between stimulus-driven and goal-directed attentional control.

Role of syllable segmentation processes in peripheral word recognition.

Previous studies of foveal visual word recognition provide evidence for a low-level syllable decomposition mechanism occurring during the recognition of a word. We investigated if such a decomposition mechanism also exists in peripheral word recognition. Single words were visually presented to subjects in the peripheral field using a 6° square gaze-contingent simulated central scotoma. In the first experiment, words were either unicolor or had their adjacent syllables segmented with two different colors (color/syllable congruent condition). Reaction times for correct word identification were measured for the two different conditions and for two different print sizes. Results show a significant decrease in reaction time for the color/syllable congruent condition compared with the unicolor condition. A second experiment suggests that this effect is specific to syllable decomposition and results from strategic, presumably involving attentional factors, rather than stimulus-driven control.

What do fast response times tell us about attentional control?

The mental experience of attention capture has attracted a great deal of intrigue among researchers seeking to explain the interactions between stimulus-driven and goal-driven attentional control. In recent years, researchers have increasingly begun to analyze cumulative response time (RT) distributions to test modern accounts of the capture phenomenon, particularly accounts claiming that there are changes in susceptibility to distraction as a function of time. In this paper, we raise a criticism of this approach, which centers on a problematic assumption. The assumption is that variability in these distributions is primarily determined by fluctuations in the observer's internal control state (e.g., readiness for the trial). However, it is also the case that faster segments of the distributions are overrepresented by trials that are objectively easy, while slower segments are overrepresented by trials that are objectively difficult. That is, incidental aspects of the trial stimuli influence task performance independently of the observer's internal control state. Here, we demonstrate empirically that contributions of incidental stimulus factors distort cumulative RT distributions in such a way that confounds proper interpretation of experimental data. The results have implications for theoretical accounts of attentional control, and they also raise caution about the assumptions that are sometimes made when analyzing cumulative RT distributions.

Joint principles of motor and cognitive dysfunction in Parkinson’s disease

Traditionally, the lateral premotor cortex (PM) is assigned a role in stimulus-driven rather than memory-driven motor control, whereas the opposite holds for the mesial premotor cortex (supplementary motor area, SMA). Consistently, patients with Parkinson’s Disease (PD), in which a specific functional degradation of the mesial loop (i.e., SMA-Striatum) occurs, show impaired memory-driven but relatively preserved stimulus-driven motor control. However, both parts of the premotor cortex are involved in perceptual prediction tasks as well. Here we tested whether the functional bias described on the motor level (i.e., memory-driven/mesial versus stimulus-driven/lateral) can also be detected in perceptual prediction tasks thereby suggesting that PD patients exhibit the same pattern of impaired memory-driven and preserved stimulus-driven control in the cognitive domain. To this end, we investigated 20 male PD-patients “on” and “off” dopaminergic medication while performing a serial prediction task (SPT). A specific modification was implemented to the classical SPT (SPT0) that caused shifts from stimulus- to memory-based prediction (SPT+). As a result, PD patients showed a significantly impaired performance “off” compared to “on” medication for SPT+, whereas no significant “on”/“off”-effects were found for SPT0. Descriptively, the “off”-performance decreased gradually with increasing demands on memory-based prediction. Furthermore, the severity of motor deficits according to the UPDRS III correlated significantly with impaired performance in SPT0 “on” medication. Importantly, an even stronger dependency was found for UPDRS III and SPT+. These findings point to a role of the SMA-striatal loop in memory-driven serial prediction beyond the motor domain.

Attention and predictions: control of spatial attention beyond the endogenous-exogenous dichotomy

The mechanisms of attention control have been extensively studied with a variety of methodologies in animals and in humans. Human studies using non-invasive imaging techniques highlighted a remarkable difference between the pattern of responses in dorsal fronto-parietal regions vs. ventral fronto-parietal (vFP) regions, primarily lateralized to the right hemisphere. Initially, this distinction at the neuro-physiological level has been related to the distinction between cognitive processes associated with strategic/endogenous vs. stimulus-driven/exogenous of attention control. Nonetheless, quite soon it has become evident that, in almost any situation, attention control entails a complex combination of factors related to both the current sensory input and endogenous aspects associated with the experimental context. Here, we review several of these aspects first discussing the joint contribution of endogenous and stimulus-driven factors during spatial orienting in complex environments and, then, turning to the role of expectations and predictions in spatial re-orienting. We emphasize that strategic factors play a pivotal role for the activation of the ventral system during stimulus-driven control, and that the dorsal system makes use of stimulus-driven signals for top-down control. We conclude that both the dorsal and the vFP networks integrate endogenous and exogenous signals during spatial attention control and that future investigations should manipulate both these factors concurrently, so as to reveal to full extent of these interactions.

Stimulus-level interference disrupts repetition benefit during task switching in middle childhood.

The task-switching paradigm provides a powerful tool to measure the development of core cognitive control processes. In this study, we use the alternating runs task-switching paradigm to assess preparatory control processes involved in flexibly preparing for a predictable change in task and stimulus-driven control processes involved in controlling stimulus-level interference. We present three experiments that examine behavioral and event-related potential (ERP) measures of task-switching performance in middle childhood and young adulthood under low and high stimulus interference conditions. Experiment 1 confirms that our new child-friendly tasks produce similar behavioral and electrophysiological findings in young adults as those previously reported. Experiment 2 examines task switching with univalent stimuli across a range of preparation intervals in middle childhood. Experiment 3 compares task switching with bivalent stimuli across the same preparation intervals in children and young adults. Children produced a larger RT switch cost than adults with univalent stimuli and a short preparation interval. Both children and adults showed significant reduction in switch cost with increasing preparation interval, but in children this was caused by greater increase in RT for repeat than switch trials. Response-locked ERPs showed intact preparation for univalent, but less efficient preparation for bivalent stimulus conditions. Stimulus-locked ERPs confirmed that children showed greater stimulus-level interference for repeat trials, especially with bivalent stimuli. We conclude that children show greater stimulus-level interference especially for repeat trials under high interference conditions, suggesting weaker mental representation of the current task set.

Unmasking the contribution of low-level features to the guidance of attention

The role of low-level stimulus-driven control in the guidance of overt visual attention has been difficult to establish because low- and high-level visual content are spatially correlated within natural visual stimuli. Here we show that impairment of parietal cortical areas, either permanently by a lesion or reversibly by repetitive transcranial magnetic stimulation (rTMS), leads to fixation of locations with higher values of low-level features as compared to control subjects or in a no-rTMS condition. Moreover, this unmasking of stimulus-driven control crucially depends on the intrahemispheric balance between top-down and bottom-up cortical areas. This result suggests that although in normal behavior high-level features might exert a strong influence, low-level features do contribute to guide visual selection during the exploration of complex natural stimuli.

Dissociating Levels of Cognitive Control

Attention is often imperfect; cognitive control is needed to counteract the tendency to attend to distractors that are incompatible with current goals. Cognitive psychologists have long explored cognitive control by examining Stroop interference—the slowed naming of colors on incongruent trials (e.g., “RED” displayed in blue ink), as compared to congruent trials (e.g., “RED” displayed in red ink), in the color-word Stroop task. The magnitude of interference reflects the effectiveness of cognitive control, but it does not reveal the precise processes used to minimize attention to the distracting word. The need for experimental approaches that accomplish this objective is underscored by the existence of qualitatively different cognitive control processes. Prior accounts stressed the use of top-down filtering processes at a task- or list-wide level to avoid word reading, but recent findings have shown that control of word reading is sometimes stimulus-driven—that is, triggered by the processing of stimuli or stimulus features. In this article, I highlight the critical findings that dissociate top-down and stimulus-driven control in the Stroop task, dissociations that are central to the view that cognitive control operates at multiple levels.

The influence of visual search efficiency on the time-course of identity-based SR-compatibility

Three experiments were conducted to investigate the impact of stimulus-driven control on the time-course of stimulus–response (SR) compatibility. Participants responded to the presence or absence of a singleton arrow that was presented among multiple nontargets. When the singleton arrow was present, observers pressed a button with their right index finger, when it was absent they pressed with their left-index finger. SR-compatibility depended on the relation between the identity of the target and the present response: Even though the identity of the target singleton arrow (whether it was pointing to the right or left) was irrelevant to the task, the direction could be corresponding (right arrow) or noncorresponding (left arrow) with a target present response (the right hand). To examine the time-course of performance target–distractor similarity was varied to increase or decrease visual search efficiency and accordingly response latency. There were three main findings. First, the results of Experiment 1 showed that observers were no faster to respond ‘present’ when the singleton arrow pointed to the right (corresponding to the right hand) than when it pointed left (noncorresponding to the right hand) in a simple present–absent detection task. Second, only when observers were encouraged to process the identity of the arrow singleton, an effect of an SR-compatibility effect was found which developed over time. Third, the time-course of SR-compatibility was not influenced by visual search efficiency. The results of the present work suggest that visual selection and response selection occur in different stages.