Pupillary correlates of lapses of sustained attention

The current study examined the extent to which pupillary responses (both pretrial baseline and phasic responses) would accurately track lapses of attention as predicted by theories of locus coeruleus norepinephrine (LC-NE) functioning. Participants performed a sustained attention task while pupil responses were continuously recorded. Periodically during the task, participants were presented with thought probes to determine if they were on or off task. The results suggested the pupillary responses accurately distinguished on from off-task states. Importantly, pretrial baseline pupil responses distinguished different types of lapses of attention, with inattentive and mind-wandering states being associated with small pretrial baseline pupil diameters on average and distracted states being associated with larger pretrial baseline pupil diameters on average compared to focused states. These results support the notion that pupil diameter is sensitive to different types of lapses of attention which may be associated with different LC-NE modes.     

Pupillary Stroop effects

We recorded the pupil diameters of participants performing the words’ color-naming Stroop task (i.e., naming the color of a word that names a color). Non-color words were used as baseline to firmly establish the effects of semantic relatedness induced by color word distractors. We replicated the classic Stroop effects of color congruency and color incongruency with pupillary diameter recordings: relative to non-color words, pupil diameters increased for color distractors that differed from color responses, while they reduced for color distractors that were identical to color responses. Analyses of the time courses of pupil responses revealed further differences between color-congruent and color-incongruent distractors, with the latter inducing a steep increase of pupil size and the former a relatively lower increase. Consistent with previous findings that have demonstrated that pupil size increases as task demands rise, the present results indicate that pupillometry is a robust measure of Stroop interference, and it represents a valuable addition to the cognitive scientist’s toolbox.     

Effects of different non-driving-related-task display modes on drivers’ eye-movement patterns during take-over in an automated vehicle

Highly automated vehicles relieve drivers from driving tasks, allowing them to engage in non-driving-related-tasks (NDRTs). However, drivers are required to take over control in certain circumstances due to the limitations of highly automated vehicles. This study focused on drivers’ eye-movement patterns during take-overs when an NDRT (watching videos) was presented via a head-up-display (HUD) and a mobile device display (MDD), compared to no NDRT as the baseline. The experiment was conducted in a high-fidelity driving simulator with real-world driving videos scenarios. Forty-six participants took part in the experiment by completing three drives in three counterbalanced conditions (HUD, MDD and baseline). A take-over-request was issued towards the end of automated driving requesting drivers to stop the NDRT and take over control. Eye-movement data including pupil diameter, blinks, glance duration and number of AOI (Area of Interest) were collected and analysed. The results show that during automated driving, drivers were more engaged in the MDD NDRT with smaller pupil diameter and shorter glance duration on the front scenario compared to the HUD and baseline modes. The number of AOI was reduced during automated driving in both MDD and HUD modes. The take-over-request redirected drivers’ visual attention back to the driving task from NDRT by increasing drivers’ pupil diameter, glance duration and number of AOI. However, the effect of MDD NDRT on pupil diameter and glance duration continued even after the take-over-request when the NDRT was terminated. The study demonstrated HUD is a better display to help maintain drivers’ attention on the road.     

Pupil dilation as an index of effort in cognitive control tasks: A review

Pupillometry research has experienced an enormous revival in the last two decades. Here we briefly review the surge of recent studies on task-evoked pupil dilation in the context of cognitive control tasks with the primary aim being to evaluate the feasibility of using pupil dilation as an index of effort exertion, rather than task demand or difficulty. Our review shows that across the three cognitive control domains of updating, switching, and inhibition, increases in task demands typically leads to increases in pupil dilation. Studies show a diverging pattern with respect to the relationship between pupil dilation and performance and we show how an effort account of pupil dilation can provide an explanation of these findings. We also discuss future directions to further corroborate this account in the context of recent theories on cognitive control and effort and their potential neurobiological substrates.     

Tracking arousal state and mind wandering with pupillometry

In four experiments, the association between arousal state and different mind-wandering states was examined. Participants performed a sustained attention task while pupil responses were continuously recorded. Periodically during the task, participants were presented with thought probes to determine if they were on task or mind wandering. Across the four experiments, the results suggested that in situations that promoted on-task behaviors and focused external attention, mind wandering was associated with lowered arousal, as seen by smaller tonic pupil diameters and smaller phasic pupillary responses. However, in situations that promoted a more internal focus of attention, there were no differences between on-task states and mind wandering in tonic pupil diameter (although differences emerged for phasic pupillary responses), suggesting similar arousal levels. Furthermore, across the four experiments, mind blanking and mind wandering dissociated in terms of whether the situation promoted focused external attention or focused internal attention. These results are broadly consistent with the notion that mind wandering is a heterogeneous construct, with different forms of mind wandering being associated with different arousal states, and suggest that a combination of behavioral and pupillary measures can be used to track these various states.     

Ocular signatures of proactive versus reactive cognitive control in young adults

During the execution of a cognitive task, the brain maintains contextual information to guide behavior and achieve desired goals. The AX-Continuous Performance Task is used to study proactive versus reactive cognitive control. Young adults tend to behave proactively in standard testing conditions. However, it remains unclear how interindividual variability (e.g., in cognitive and motivational factors) may drive people into more reactive or proactive control under the same task demands. We investigated the use of control strategies in a large population of healthy young adults. We computed the proactive behavioral index and consequently divided participants into proactive, reactive, and intermediate groups. We found that reactive participants were generally slower, presented lower context sensitivity, and larger response variability. Pupillary changes and blink rate index cognitive effort allocation. We measured, concomitantly to the task, the pupil size and frequency of blinks associated with the cue maintenance and response intervals. During the cue period, nonfrequent, nontarget cues led to increased pupil dilation and number of blinks in all participants. During the response interval, we found more errors and increased pupil dilation to the probe when all participants had to overcome a response bias generated by the frequent cue. Only reactive participants showed larger response-related pupil when they had to overcome a response bias related to the frequent probe. Contrary to expectations, groups did not differ in ocular measures in the cue period. In conclusion, interindividual differences in cognitive control between healthy adults can be mapped onto different patterns of effort allocation indexed by the pupil.     

Pupil Diameter May Reflect Motor Control and Learning

Non–luminance-mediated changes in pupil diameter have been used since the first studies by Darwin in 1872 as indicators of clinical, cognitive, and arousal states. However, the relation between processes involved in motor control and changes in pupil diameter remains largely unknown. Twenty participants attempted to compensate random walks of a cursor with a computer mouse to restrain its trajectory within a target circle while the authors recorded their pupil diameters. Two conditions allowed the authors to experimentally manipulate the motor and cognitive components of the task. First, the step size of the cursor's random walk was either large or small leading to 2 task difficulties (difficult or easy). Second, they instructed participants to imagine controlling the cursor by moving the mouse, but without actually moving it (task modality: imagined movement or real movement condition). Task difficulty and modality allowed the authors to show that pupil diameters reflect processes involved in motor control and in the processing of feedback, respectively. Furthermore, the authors also demonstrate that motor learning can be quantified by pupil size. This noninvasive approach provides a promising method for investigating not only motor control, but also motor imagery, a research field of growing importance in sports and rehabilitation.     

眼动技术在个体认知能力差异研究中的应用

本文从可能性和可行性两方面介绍和论述了眼动技术在个体认知能力差异研究中的应用。在可能性方面,个体眼动特征具有的良好的重测信度和内部一致性信度;在可行性方面,已有研究利用注视和眼跳相关指标、眼动轨迹和瞳孔直径这三类指标对该问题进行探索,结果均发现这些眼动特征与认知能力之间存在着密切关系。今后研究应继续深入探索两者关系的内在认知和神经机制,并尝试结合人工智能算法开发高信效度的眼动认知测验。     

Can pupillometry index auditory attentional capture in contexts of active visual processing?

The rare presentation of a sound that deviates from the auditory background tends to capture attention, which is known to impede cognitive functioning. Such disruption is usually measured using performance on a concurrent visual task. Growing evidence recently showed that the pupillary dilation response (PDR) could index the attentional response triggered by a deviant sound. Given that the pupil diameter is sensitive to several vision-related factors, it is unclear whether the PDR could serve to study attentional capture in such contexts. Hence, the present study aimed at verifying whether the PDR can be used as a proxy for auditory attentional capture while a visual serial recall task (Experiment 1) or a reading comprehension task (Experiment 2) – respectively producing changes in luminance and gaze position – is being performed. Results showed that presenting a deviant sound within steady-state standard sounds elicited larger PDRs than a standard sound. Moreover, the magnitude of these PDRs was positively related to the amount of performance disruption produced by deviant sounds in Experiment 1. Performance remained unaffected by the deviants in Experiment 2, thereby implying that the PDR may be a more sensitive attention-capture index than behavioural measures. These results suggest that the PDR can be used to assess attentional capture by a deviant sound in contexts where the pupil diameter can be modulated by the visual environment.     

Increased locus coeruleus tonic activity causes disengagement from a patch-foraging task

High levels of locus coeruleus (LC) tonic activity are associated with distraction and poor performance within a task. Adaptive gain theory (AGT; Aston-Jones & Cohen, 2005) suggests that this may reflect an adaptive function of the LC, encouraging search for more remunerative opportunities in times of low utility. Here, we examine whether stimulating LC tonic activity using designer receptors (DREADDs) promotes searching for better opportunities in a patch-foraging task as the value of a patch diminishes. The task required rats to decide repeatedly whether to exploit an immediate but depleting reward within a patch or to incur the cost of a time delay to travel to a new, fuller patch. Similar to behavior associated with high LC tonic activity in other tasks, we found that stimulating LC tonic activity impaired task performance, resulting in reduced task participation and increased response times and omission rates. However, this was accompanied by a more specific, predicted effect: a significant tendency to leave patches earlier, which was best explained by an increase in decision noise rather than a systematic bias to leave earlier (i.e., at higher values). This effect is consistent with the hypothesis that high LC tonic activity favors disengagement from current behavior, and the pursuit of alternatives, by augmenting processing noise. These results provide direct causal evidence for the relationship between LC tonic activity and flexible task switching proposed by AGT.     

Reappraising faces: effects on accountability appraisals,self-reported valence,and pupil diameter

Many of our emotions arise in social contexts, as we interact with and learn about others. What is not yet clear, however, is how such emotions unfold when we either react to others or attempt to regulate our emotions. To address this issue, 30 healthy volunteers reacted to or reappraised positive or negative information that was paired with neutral faces. While they were doing this task, we assessed pupillary responses. We also asked participants to provide ratings of accountability and experienced emotion. Findings indicated that appraised accountability increased in response to emotional information, and changes in accountability were associated with commensurate changes in valence reports and increased pupil diameter. During reappraisal, accountability and emotion decreased, but pupil diameter increased. The findings highlight the importance of accountability appraisals during the generation and regulation of emotional reactions to others, while also documenting pupillary increases during emotional reactivity and regulation.     

Motivational influences on cognitive control: Behavior,brain activation,and individual differences

What changes in brain activity are associated with changes in motivational state? The present study addressed this question by having participants perform a cognitive task (AX variant of the Continuous Performance Test; AX-CPT) under three different blocked motivational conditions (reward-incentive, penalty-incentive, and baseline). Behavioral data showed that the incentive conditions modulated task performance, potentially by altering participants’ cognitive control strategy. Neuroimaging data indicated that the reward condition was associated with a sustained increase in a primarily right-lateralized network that included parietal and prefrontal cortex. Additionally, individual differences were observed, such that activation in both reward-related brain regions and frontopolar cortex was linked to the degree of motivation-induced performance enhancement and to motivation-related personality variables. These results suggest that changes in motivational state may modulate performance through sustained activity in cognitive control regions and that the effect of incentives may be affected by the personalities of the participants.     

Simple Threshold Rules Solve Explore/Exploit Trade-offs in a Resource Accumulation Search Task

How, and how well, do people switch between exploration and exploitation to search for and accumulate resources? We study the decision processes underlying such exploration/exploitation trade-offs using a novel card selection task that captures the common situation of searching among multiple resources (e.g., jobs) that can be exploited without depleting. With experience, participants learn to switch appropriately between exploration and exploitation and approach optimal performance. We model participants' behavior on this task with random, threshold, and sampling strategies, and find that a linear decreasing threshold rule best fits participants' results. Further evidence that participants use decreasing threshold-based strategies comes from reaction time differences between exploration and exploitation; however, participants themselves report non-decreasing thresholds. Decreasing threshold strategies that “front-load” exploration and switch quickly to exploitation are particularly effective in resource accumulation tasks, in contrast to optimal stopping problems like the Secretary Problem requiring longer exploration.     

瞳孔变化在记忆加工中的生物标记作用

瞳孔在不同记忆任务的同一加工阶段内具有变化模式的一致性, 瞳孔的缩放变化反映了信息加工过程中神经系统的激活状态。在刺激呈现前的预编码阶段, 瞳孔随个体注意集中水平的提高而收缩。在信息编码阶段, 瞳孔扩张程度作为相继记忆效应的生物标记, 可预测信息未来提取阶段的回忆成绩。在信息提取阶段, 采用自由回忆任务时, 瞳孔随记忆负荷的释放而迅速收缩, 但每个项目的提取均会引发小幅度瞳孔扩张; 而在再认提取任务中, 呈现旧刺激比呈现新刺激时瞳孔扩张更明显, 产生瞳孔新旧效应。瞳孔是记忆加工中敏感而稳定的生物标记, 而瞳孔测量法是探究记忆加工生理机制的有效手段。未来可以从瞳孔追踪术的角度, 采用多种研究手段进一步探究记忆的生理机制。     

Orienting of attention, pupil size, and the norepinephrine system

This research examined a novel suggestion regarding the involvement of the locus coeruleus-norepinephrine (LC-NE) system in orienting reflexive (exogenous) attention. A common procedure for studying exogenous orienting of attention is Posner's cuing task. Importantly, one can manipulate the required level of target processing by changing task requirements, which, in turn, can elicit a different time course of inhibition of return (IOR). An easy task (responding to target location) produces earlier onset IOR, whereas a demanding task (responding to target identity) produces later onset IOR. Aston-Jones and Cohen (Annual Review of Neuroscience, 28, 403-450, 2005) presented a theory suggesting two different modes of LC activity: tonic and phasic. Accordingly, we suggest that in the more demanding task, the LC-NE system is activated in phasic mode, and in the easier task, it is activated in tonic mode. This, in turn, influences the appearance of IOR. We examined this suggestion by measuring participants' pupil size, which has been demonstrated to correlate with the LC-NE system, while they performed cuing tasks. We found a response-locked phasic dilation of the pupil in the discrimination task, as compared with the localization task, which may reflect different firing modes of the LC-NE system during the two tasks. We also demonstrated a correlation between pupil size at the time of cue presentation and magnitude of IOR.     

A computational model of fractionated conflict-control mechanisms in task-switching

A feature of human cognition is the ability to monitor and adjust one's own behavior under changing circumstances. A dynamic balance between controlled and rapid responding is needed to adapt to a fluctuating environment. We suggest that cognitive control may include, among other things, two distinct processes. Incongruent stimuli may drive top-down facilitation of task-relevant responses to bias performance toward exploitation vs. exploration. Task or response switches may generally slow responses to bias toward accuracy vs. speed and exploration vs. exploitation. Behavioral results from a task switching study demonstrate these two distinct processes as revealed by higher-order sequential effects. A computational model implements the two conflict-control mechanisms, which allow it to capture many complex and novel sequential effects. Lesion studies with the model demonstrate that the model is unable to capture these effects without the conflict-control loops and show how each monitoring component modulates cognitive control. The results suggest numerous testable predictions regarding the neural substrates of cognitive control.     

Effort during visual search and counting: insights from pupillometry

We investigated the processing effort during visual search and counting tasks using a pupil dilation measure. Search difficulty was manipulated by varying the number of distractors as well as the heterogeneity of the distractors. More difficult visual search resulted in more pupil dilation than did less difficult search. These results confirm a link between effort and increased pupil dilation. The pupil dilated more during the counting task than during target-absent search, even though the displays were identical, and the two tasks were matched for reaction time. The moment-to-moment dilation pattern during search suggests little effort in the early stages, but increasingly more effort towards response, whereas the counting task involved an increased initial effort, which was sustained throughout the trial. These patterns can be interpreted in terms of the differential memory load for item locations in each task. In an additional experiment, increasing the spatial memory requirements of the search evoked a corresponding increase in pupil dilation.These results support the view that search tasks involve some, but limited, memory for item locations, and the effort associated with this memory load increases during the trials. In contrast, counting involves a heavy locational memory component from the start.     

Effects of mothers' locus of control for child improvement in a developmentally delayed sample

A potentially important variable that has received little attention in the literature is the locus of control (LOC) a caregiver holds for child improvement, including its influence on the caregiver's treatment compliance and on actual child improvement. In this study, 131 mother-child dyads were assessed across 1 year, to evaluate the utility of the LOC construct in a practice setting. Children were approximately 4 years old at the first assessment, and all of them had been diagnosed with a developmental disability. Mothers' compliance with treatment (mothers' attendance at sessions; teachers' ratings of mothers' support and knowledge) was tracked, and measures of child development status and mothers' locus of control were administered. Statistical results indicated that mothers' locus of control was not significantly correlated with children's gains in development over the year. The mothers' beliefs about whether the child or chance would be responsible for improvement were associated with lower compliance with treatment, whereas the mothers' beliefs that child improvement was attributable to professional intervention were associated with enhanced involvement in treatment.     

Search Strategies in Practice: Testing the Effect of Inherent Variability on Search Patterns

Abstract

To execute a motor solution to a given task, individuals search through the space of movement possibilities guided by information that arises from the interaction with task and environment. Through this search, individuals seek to avoid inappropriate solutions through local minima in the task space. The processes that lead to some but not all individuals avoiding local minima and finding solutions is not yet understood. Based on the tenets of ecological psychology for perception and action, we examined in two experiments the hypothesis that the incapacity to differentiate errors (performance of an inappropriate solution) from inherent variability would interfere with the perception of properties of the task space and result in a longer time performing an inappropriate solution for the task before exploration of other solutions. Inherent variability was shown to be a direct predictor of the changes in the search strategies. Also, we found that the specifics of the search patterns could predict the performance in the task. Thus, the pattern of motion through the task space affords perception of specific properties of this space guiding individuals in the evolving dynamics of exploration or exploitation.     

Effort during visual search and counting: Insights from pupillometry

We investigated the processing effort during visual search and counting tasks using a pupil dilation measure. Search difficulty was manipulated by varying the number of distractors as well as the heterogeneity of the distractors. More difficult visual search resulted in more pupil dilation than did less difficult search. These results confirm a link between effort and increased pupil dilation. The pupil dilated more during the counting task than during target-absent search, even though the displays were identical, and the two tasks were matched for reaction time. The moment-to-moment dilation pattern during search suggests little effort in the early stages, but increasingly more effort towards response, whereas the counting task involved an increased initial effort, which was sustained throughout the trial. These patterns can be interpreted in terms of the differential memory load for item locations in each task. In an additional experiment, increasing the spatial memory requirements of the search evoked a corresponding increase in pupil dilation.These results support the view that search tasks involve some, but limited, memory for item locations, and the effort associated with this memory load increases during the trials. In contrast, counting involves a heavy locational memory component from the start.