Perceptual Load Task Research Articles

Is processing superiority a universal trait for all threats? Divergent impacts of fearful, angry, and disgusted faces on attentional capture

Fearful, angry, and disgusted facial expressions are evolutionarily salient and convey different types of threat signals. However, it remains unclear whether these three expressions impact sensory perception and attention in the same way. The present ERP study investigated the temporal dynamics underlying the processing of different types of threatening faces and the impact of attentional resources employed during a perceptual load task. Participants were asked to judge the length of bars superimposed over faces presented in the center of the screen. A mass univariate statistical approach was used to analyze the EEG data. Behaviorally, task accuracy was significantly reduced following exposure to fearful faces relative to neutral distractors, independent of perceptual load. The ERP results revealed that the P1 amplitude over the right hemisphere was found to be enhanced for fearful relative to disgusted faces, reflecting the rapid and coarse detection of fearful cues. The N170 responses elicited by fearful, angry, and disgusted faces were larger than those elicited by neutral faces, suggesting the largely automatic and preferential processing of threats. Furthermore, the early posterior negativity (EPN) component yielded increased responses to fearful and angry faces, indicating prioritized attention to stimuli representing acute threats. Additionally, perceptual load exerted a pronounced influence on the EPN and late positive potential (LPP), with larger responses observed in the low perceptual load condition, indicating goal-directed cognitive processing. Overall, the early sensory processing of fearful, angry, and disgusted faces is characterized by differential sensitivity in capturing attention automatically, despite the importance of these facial signals for survival. Fearful faces produce a strong interference effect and are processed with higher priority than angry and disgusted ones.

Face and emotional expression processing under continuous perceptual load tasks: An ERP study

High perceptual load is thought to impair already the early stages of visual processing of task-irrelevant visual stimuli. However, recent studies showed no effects of perceptual load on early ERPs in response to task-irrelevant emotional faces. In this preregistered EEG study (N = 40), we investigated the effects of continuous perceptual load on ERPs to fearful and neutral task-irrelevant faces and their phase-scrambled versions. Perceptual load did not modulate face or emotion effects for the P1 or N170. In contrast, larger face-scramble and fearful-neutral differentiation were found during low as compared to high load for the Early Posterior Negativity (EPN). Further, face-independent P1, but face-dependent N170 emotional modulations were observed. Taken together, our findings show that P1 and N170 face and emotional modulations are highly resistant to load manipulations, indicating a high degree of automaticity during this processing stage, whereas the EPN might represent a bottleneck in visual information processing.

Computational modelling of attentional bias towards threat in paediatric anxiety

Computational modelling can be used to precisely characterize the cognitive processes involved in attentional biases towards threat, yet so far has only been applied in the context of adult anxiety. Furthermore, studies investigating attentional biases in childhood anxiety have largely used tasks that conflate automatic and controlled attentional processes. By using a perceptual load paradigm, we separately investigate contributions from automatic and controlled processes to attentional biases towards negative stimuli and their association with paediatric anxiety. We also use computational modelling to investigate these mechanisms in children for the first time. In a sample of 60 children (aged 5‐11 years) we used a perceptual load task specifically adapted for children, in order to investigate attentional biases towards fearful (compared with happy and neutral) faces. Outcome measures were reaction time and percentage accuracy. We applied a drift diffusion model to investigate the precise cognitive mechanisms involved. The load effect was associated with significant differences in response time, accuracy and the diffusion modelling parameters drift rate and extra‐decisional time. Greater anxiety was associated with greater accuracy and the diffusion modelling parameter ‘drift rate’ on the fearful face trials. This was specific to the high load condition. These findings suggest that attentional biases towards fearful faces in childhood anxiety are driven by increased perceptual sensitivity towards fear in automatic attentional systems. Our findings from computational modelling suggest that current attention bias modification treatments should target perceptual encoding directly rather than processes occurring afterwards.

Ingested but not perceived: Response to satiety cues disrupted by perceptual load

Selective attention research has shown that when perceptual demand is high, unattended sensory information is filtered out at early stages of processing. We investigated for the first time whether the sensory and nutrient cues associated with becoming full (satiety) would be filtered out in a similar manner. One-hundred and twenty participants consumed either a low-satiety (75 kcal) or high-satiety (272 kcal plus thicker texture) beverage, delivered via an intra-oral infusion device while participants simultaneously completed a task which was either low or high in perceptual demand. Among participants who performed the low perceptual load task, ingestion of the high-satiety beverage increased rated satiety and reduced consumption at a subsequent snack test. However, both effects were eliminated by the high perceptual load task. Therefore, the processing of satiety cues was dependent on the availability of attention, identifying a novel perceptual load mechanism of inattentive eating and supporting more recent cognitive models of appetite control.

A high perceptual load task reduces thoughts about chocolate, even while hungry

Intrusive thoughts about food can trigger cravings and result in unhealthy eating behaviour. Here we tested whether Load Theory of attention can be applied to the eating behaviour literature and reduce intrusive appetitive-related thoughts. Load Theory predicts that high levels of perceptual load in a task exhaust attentional capacity and so reduces interference from a range of stimuli, including intrusive thoughts. Therefore, this study aimed to test whether perceptual load reduced appetitive-related intrusive thoughts about chocolate. Sixty female participants were first given a chocolate bar to interact with for 2 min, before rating their levels of hunger, craving and liking for chocolate. They were then asked to avoid thinking about chocolate and instead focus attention on a visual search task. Perceptual load was manipulated within-subjects by varying the search set size. Appetitive-related thoughts were measured using both self-caught and probe-caught measures, allowing us to index load effects at varying levels of meta-awareness. Across subjects, the level of appetitive-related thoughts seen in the high load condition was significantly reduced, to less than half the level seen in the low load condition, on both probe and self-caught measures. Furthermore, self-reported hunger, craving and liking for the chocolate were positively correlated with appetitive-related thoughts under low load, but high perceptual load eliminated these state individual differences. Therefore, engaging in perceptually demanding tasks may be a worthwhile strategy for those wanting to disrupt the cycle of craving at the earliest stage.

A high perceptual load task reduces food-related intrusive thoughts

A high perceptual load task reduces food-related intrusive thoughts

Attentional control underlies the perceptual load effect: Evidence from voxel-wise degree centrality and resting-state functional connectivity

The fact that interference from peripheral distracting information can be reduced in high perceptual load tasks has been widely demonstrated in previous research. The modulation from the perceptual load is known as perceptual load effect (PLE). Previous functional magnetic resonance imaging (fMRI) studies on perceptual load have reported the brain areas implicated in attentional control. To date, the contribution of attentional control to PLE and the relationship between the organization of functional connectivity and PLE are still poorly understood. In the present study, we used resting-state fMRI to explore the association between the voxel-wise degree centrality (DC) and PLE in an individual differences design and further investigated the potential resting-state functional connectivity (RSFC) contributing to individual’s PLE. DC-PLE correlation analysis revealed that PLE was positively associated with the right middle temporal visual area (MT)—one of dorsal attention network (DAN) nodes. Furthermore, the right MT functionally connected to the conventional DAN and the RSFCs between right MT and DAN nodes were also positively associated with individual difference in PLE. The results suggest an important role of attentional control in perceptual load tasks and provide novel insights into the understanding of the neural correlates underlying PLE.

Putting attention in the spotlight: The influence of APOE genotype on visual search in mid adulthood

The Apolipoprotein E e4 allele is associated with greater cognitive decline with age, yet effects of this gene are also observed earlier in the lifespan. This research explores genotype differences (e2, e3, e4) in the allocation of visuospatial attention in mid-adulthood. Sixty-six volunteers, aged 45–55 years, completed two paradigms probing the active selection of information at the focus of attention (a dynamic scaling task) and perceptual capacity differences. Two methods of statistical comparison (parametric statistics, Bayesian inference) found no significant difference between e4 carriers and the homozygous e3 group on either the dynamic scaling or perceptual load task. E2 carriers, however, demonstrated less efficient visual search performance on the dynamic scaling task. The lack of an e4 difference in visuospatial attention, despite previous suggestion in the literature of genotype effects, indicates that select attentional processes are intact in e4 carriers in mid-adulthood. The association of e2 genotype with slower visual search performance complicates the premised protective effects of this allele in cognitive ageing.

Effects of working memory contents and perceptual load on distractor processing: When a response-related distractor is held in working memory

Working memory and attention are closely related. Recent research has shown that working memory can be viewed as internally directed attention. Working memory can affect attention in at least two ways. One is the effect of working memory load on attention, and the other is the effect of working memory contents on attention. In the present study, an interaction between working memory contents and perceptual load in distractor processing was investigated. Participants performed a perceptual load task in a standard form in one condition (Single task). In the other condition, a response-related distractor was maintained in working memory, rather than presented in the same stimulus display as a target (Dual task). For the Dual task condition, a significant compatibility effect was found under high perceptual load; however, there was no compatibility effect under low perceptual load. These results suggest that the way the contents of working memory affect visual search depends on perceptual load.

Attention Moderates the Relationship Between Primary Psychopathy and Affective Empathy in Undergraduate Students.

Psychopathy is personality traits, which is consisted of primary psychopathy characterized by affective and interpersonal problems and secondary psychopathy characterized by behavioral problems. Prior researchers have suggested that people with psychopathy have peculiar attention, which prevents them from detecting information peripheral to their concern, and we hypothesized that this explains their low empathy. Based on these reasoning, the present study assessed whether attention moderates the relationship between psychopathy and affective empathy. Eighty-five undergraduates (40 men and 45 women; mean age = 19.8 years; SD = 1.6) completed the Levenson Self-Report Psychopathy Scale, the Interpersonal Reactivity Index, and a perceptual load task. Hierarchical regression showed that a significant moderation effect was found: primary psychopathy was negatively associated with affective empathy, among those with reduced interference from task-irrelevant stimuli under a medium level of perceptual load. Future study should need to replicate this finding with clinical population.

TESTING LOAD THEORY OF ATTENTION: IGNORING IRRELEVANT DISTRACTOR

Load theory of attention suggests that insufficient capacity for processing prevents subjects from perceiving irrelevant distractor in high perceptual load tasks (LaVie et al, 2004). The aim of our research was to test the proposed theory in visual search task, sinceLavie et al used choice response task in their research. Participants were asked to search for the oblique line among horizontal or vertical ones, while ignoring irrelevant distractor. The independent variables were target presence, task difficulty (depending on the angle of rotation of the target), distractor (there was either no distractor, or the distractor was oriented in the same direction as the target or in the opposite direction) and set size. The dependent variable was reaction time. Only target-present sets were analyzed. Significant effects of the task difficulty (F(1,11)=118.05, p=.000) and distractor (F(2,22)=17.436, p<.01) factors were obtained, as well as significant interaction of task difficulty and distractor (F(2,22)=17.281, p<.01). Analysis showed that in simple tasks there was no effect of irrelevant distractors. In difficult tasks, reaction times were the shortest when there was no irrelevant distractor and the longest when the distractor was rotated in the opposite direction from that of the target. The obtained results suggest that irrelevant distractor disturbs performance only in high perceptual load task, which is not in line withthe assumptions of the load theory.

Automatic imitation? Imitative compatibility affects responses at high perceptual load.

Imitation involves matching the visual representation of another's action onto the observer's own motor program for that action. However, there has been some debate regarding the extent to which imitation is "automatic"-that is, occurs without attention. Participants performed a perceptual load task in which images of finger movements were presented as distractors. Responses to target letter stimuli were performed via finger movements that could be imitatively compatible (requiring the same finger movement) or incompatible with the distractor movements: In this common stimulus-response compatibility manipulation, the stimulus set comprises images of the response movements, producing an imitative compatibility effect. Attention to the distractor movements was manipulated by altering perceptual load through increasing the number of nontarget letter stimuli. If imitation requires attention, then at high perceptual load, imitative compatibility should not affect response times. In contrast, imitative compatibility influenced response times at high perceptual load, demonstrating that distractor movements were processed. However, the compatibility effect was reversed, suggesting that longer response times at high perceptual load tap into an inhibitory stage of distractor movement processing. A follow-up experiment manipulating temporal delay between targets and distractor movements supported this explanation. Further experiments confirmed that nonmovement distractor stimuli in the same configuration produced standard perceptual load effects and that results were not solely due to effector compatibility. These data suggest that imitation can occur without attention. (PsycINFO Database Record

Using Task-Induced Pupil Diameter and Blink Rate to Infer Cognitive Load

Minimizing user cognitive load is suggested as an integral part of human-centered design, where a more intuitive, easy to learn, and adaptive interface is desired. In this context, it is difficult to develop optimal strategies to improve the design without first knowing how user cognitive load fluctuates during interaction. In this study, we investigate how cognitive load measurement is affected by different task types from the perspective of the load theory of attention, using pupil diameter and blink measures. We induced five levels of cognitive load during low and high perceptual load tasks and found that although pupil diameter showed significant effects on cognitive load when the perceptual load was low, neither blink rate nor pupil diameter showed significant effects on cognitive load when the perceptual load was high. The results indicate that pupil diameter can index cognitive load only in the situation of low perceptual load and are the first to provide empirical support for the cognitive control aspect of the load theory of attention, in the context of cognitive load measurement. Meanwhile, blink is a better indicator of perceptual load than cognitive load. This study also implies that perceptual load should be considered in cognitive load measurement using pupil diameter and blink measures. Automatic detection of the type and level of load in this manner helps pave the way for better reasoning about user internal processes for human-centered interface design.

Neural control of vascular reactions: impact of emotion and attention.

This study investigated the neural regions involved in blood pressure reactions to negative stimuli and their possible modulation by attention. Twenty-four healthy human subjects (11 females; age = 24.75 ± 2.49 years) participated in an affective perceptual load task that manipulated attention to negative/neutral distractor pictures. fMRI data were collected simultaneously with continuous recording of peripheral arterial blood pressure. A parametric modulation analysis examined the impact of attention and emotion on the relation between neural activation and blood pressure reactivity during the task. When attention was available for processing the distractor pictures, negative pictures resulted in behavioral interference, neural activation in brain regions previously related to emotion, a transient decrease of blood pressure, and a positive correlation between blood pressure response and activation in a network including prefrontal and parietal regions, the amygdala, caudate, and mid-brain. These effects were modulated by attention; behavioral and neural responses to highly negative distractor pictures (compared with neutral pictures) were smaller or diminished, as was the negative blood pressure response when the central task involved high perceptual load. Furthermore, comparing high and low load revealed enhanced activation in frontoparietal regions implicated in attention control. Our results fit theories emphasizing the role of attention in the control of behavioral and neural reactions to irrelevant emotional distracting information. Our findings furthermore extend the function of attention to the control of autonomous reactions associated with negative emotions by showing altered blood pressure reactions to emotional stimuli, the latter being of potential clinical relevance.

Visual short-term memory load strengthens selective attention

Perceptual load theory accounts for many attentional phenomena; however, its mechanism remains elusive because it invokes underspecified attentional resources. Recent dual-task evidence has revealed that a concurrent visual short-term memory (VSTM) load slows visual search and reduces contrast sensitivity, but it is unknown whether a VSTM load also constricts attention in a canonical perceptual load task. If attentional selection draws upon VSTM resources, then distraction effects-which measure attentional "spill-over"-will be reduced as competition for resources increases. Observers performed a low perceptual load flanker task during the delay period of a VSTM change detection task. We observed a reduction of the flanker effect in the perceptual load task as a function of increasing concurrent VSTM load. These findings were not due to perceptual-level interactions between the physical displays of the two tasks. Our findings suggest that perceptual representations of distractor stimuli compete with the maintenance of visual representations held in memory. We conclude that access to VSTM determines the degree of attentional selectivity; when VSTM is not completely taxed, it is more likely for task-irrelevant items to be consolidated and, consequently, affect responses. The "resources" hypothesized by load theory are at least partly mnemonic in nature, due to the strong correspondence they share with VSTM capacity.

Perceptual load corresponds with factors known to influence visual search.

One account of the early versus late selection debate in attention proposes that perceptual load determines the locus of selection. Attention selects stimuli at a late processing level under low-load conditions but selects stimuli at an early level under high-load conditions. Despite the successes of perceptual load theory, a noncircular definition of perceptual load remains elusive. We investigated the factors that influence perceptual load by using manipulations that have been studied extensively in visual search, namely target-distractor similarity and distractor-distractor similarity. Consistent with previous work, search was most efficient when targets and distractors were dissimilar and the displays contained homogeneous distractors; search became less efficient when target-distractor similarity increased irrespective of display heterogeneity. Importantly, we used these same stimuli in a typical perceptual load task that measured attentional spillover to a task-irrelevant flanker. We found a strong correspondence between search efficiency and perceptual load; stimuli that generated efficient searches produced flanker interference effects, suggesting that such displays involved low perceptual load. Flanker interference effects were reduced in displays that produced less efficient searches. Furthermore, our results demonstrate that search difficulty, as measured by search intercept, has little bearing on perceptual load. We conclude that rather than be arbitrarily defined, perceptual load might be defined by well-characterized, continuous factors that influence visual search.

Perceptual load in sport and the heuristic value of the perceptual load paradigm in examining expertise-related perceptual-cognitive adaptations

In two experiments, we transferred perceptual load theory to the dynamic field of team sports and tested the predictions derived from the theory using a novel task and stimuli. We tested a group of college students (N = 33) and a group of expert team sport players (N = 32) on a general perceptual load task and a complex, soccer-specific perceptual load task in order to extend the understanding of the applicability of perceptual load theory and further investigate whether distractor interference may differ between the groups, as the sport-specific processing task may not exhaust the processing capacity of the expert participants. In both, the general and the specific task, the pattern of results supported perceptual load theory and demonstrates that the predictions of the theory also transfer to more complex, unstructured situations. Further, perceptual load was the only determinant of distractor processing, as we neither found expertise effects in the general perceptual load task nor the sport-specific task. We discuss the heuristic utility of using response-competition paradigms for studying both general and domain-specific perceptual-cognitive adaptations.

Amygdala activation to fearful faces under attentional load

While some functional imaging studies suggested an automatic activation of the amygdala to fearful vs. neutral faces, recent studies showed the absence of amygdala activation to fearful faces under high attentional load induced by distracting tasks. The present fMRI study investigated whether this outcome can be modulated by changing the saliency of the eyes of fearful faces. Subjects had to solve a high perceptual load task while they were presented either with normal faces (Exp. 1) or with normal faces intermixed with faces, in which pupil and iris of eyes were erased to increase the saliency of the normal eyes (Exp. 2). There was no differential amygdala activation to fearful versus neutral faces under standard conditions without any manipulation of the faces (Exp. 1). In contrast to this outcome, Experiment 2 led to differential amygdala activation to the normal but not to the manipulated fearful vs. neutral faces. These findings propose a concept of relative automaticity of the activation of the amygdala. The activation depends on available cognitive resources and on the saliency of specific parts of fearful faces.

Attention and the readiness for action

The initiation of voluntary action is preceded by up to 2s of preparatory neural activity, originating in premotor and supplementary motor regions of the brain. The function of this extended period of pre-movement activity is unclear. Although recent studies have suggested that pre-movement activity is influenced by attention to action, little is understood about the specific processes that are involved in this preparatory period prior to voluntary action. We recorded readiness potentials averaged from EEG activity as participants made voluntary self-paced finger movements. We manipulated the processing resources available for action preparation using concurrent perceptual load and cognitive working memory load tasks. Results showed that pre-movement activity was significantly reduced only under conditions of high working memory load, when resources for planning action were limited by the concurrent cognitive load task. In contrast, limiting attentional resources in the perceptual load task had no effect on pre-movement readiness activity. This suggests that movement preparatory processes involve mechanisms of cognitive control that are also required for working memory, and not more general engagement of selective attentional resources. We propose that the extended period of pre-movement neural activity preceding voluntary action reflects the engagement of cognitive control mechanisms for endogenously orienting attention in time, in readiness for the initiation of voluntary action.

Individual differences at high perceptual load: The relation between trait anxiety and selective attention

Attentional control theory (Eysenck et al., 2007) posits that taxing attentional resources impairs performance efficiency in anxious individuals. This theory, however, does not explicitly address if or how the relation between anxiety and attentional control depends upon the perceptual demands of the task at hand. Consequently, the present study examined the relation between trait anxiety and task performance using a perceptual load task (Maylor & Lavie, 1998). Sixty-eight male college students completed a visual search task that indexed processing of irrelevant distractors systematically across four levels of perceptual load. Results indicated that anxiety was related to difficulty suppressing the behavioural effects of irrelevant distractors (i.e., decreased reaction time efficiency) under high, but not low, perceptual loads. In contrast, anxiety was not associated with error rates on the task. These findings are consistent with the prediction that anxiety is associated with impairments in performance efficiency under conditions that tax attentional resources.