The Development of Selective Attention in Children With Attention Deficit Hyperactivity Disorder

The influence of age on a selective attention task was studied in a sample of children with and without Attention Deficit Hyperactivity Disorder (ADHD). The impact of methylphenidate (MPH) treatment on selective attention was also investigated in the children with ADHD. Two age groups of children with ADHD and two age groups of control children were tested using a timed computer task. The task consisted of identifying visual target stimuli under various distracter conditions. Distracters varied on the basis of modality (i.e., visual, auditory, or both) and task relevance (i.e., meaningful or irrelevant). Reaction times and accuracy were measured. Children with ADHD were less efficient on the selective attention task than were children without ADHD, and older children were more efficient than younger children in both groups. Children without ADHD were influenced more by the nature of distracters than were children with ADHD. For children with ADHD, MPH improved performance overall.     

The effects of nodality on the formation of equivalence classes

A four-member equivalence class (A → B → C → D) can be formed by training AB, BC, and CD. The nodal stimuli, B and C, mediate all of the derivative (transitive and equivalence) relations in the class. The derivative relations AC, CA, BD, and DB are separated by one node, whereas AD and DA are separated by two nodes. How do the number of nodes that separate the stimuli in a derivative relation influence the induction of stimulus control exerted by that relation? Seven college students learned two four-member classes made up of nonsense syllables. After training, all derivative relations were presented repeatedly without informative feedback. Stimulus control exerted by each derivative relation was assessed concurrently. For the 7 subjects, control exerted by the derivative relations increased gradually with repeated presentations. With 6 of the 7 subjects, the one-node relations exerted more control than the two-node relations during the process. However, the disparity between the one- and two-node relations decreased with repeated presentations. Eventually, all derivative relations exerted complete control. The control exerted by derivative relations during induction was inversely related to the number of nodes separating the terms in the derivative relations. These results demonstrate that nodal distance is a determinant of the relatedness of stimuli in equivalence classes. The findings are discussed in terms of remote association, semantic memory networks, and the study of transitive inference.     

The effects of acute resistance exercise on young and older males' working memory

ObjectivesThe aim of the current study was two-fold: to examine the effects of acute, moderate intensity resistance exercise (RE) on working memory in young and older males, respectively.DesignA two-study approach with a within-subjects design.MethodsStudy 1 recruited 20 young males aged 21–30 years. Participants underwent two experimental sessions, the exercise session and reading session, in a counterbalanced order. The RE protocol included two sets of 10 repetitions at 70% of 10-repetition maximum of eight muscle exercises. The Sternberg working memory paradigm with two probe types (in-set probes and out-of-set probes) was used as the cognitive task where reaction times (RT) and response accuracy were identified. Study 2 recruited 20 older male adults aged 65–72 years. The methods and experimental procedures were the same as Study 1.ResultsIn Study 1, young males demonstrated shorter RTs after the exercise treatment as compared with the reading treatment for both probe types. In Study 2, older males showed shorter RTs after the exercise treatment as compared with the reading treatment in the out-of-set probes only.ConclusionsWhile acute RE benefited working memory in both young and older males, rather than general facilitation, it was shown to have a disproportionately larger effect on older males for tasks involving higher working memory demands.     

Role of frontal cortex in attentional capture by singleton distractors

The role of frontal cortex in selective attention to visual distractors was examined in an attentional capture task in which participants searched for a unique shape in the presence or absence of an additional colour singleton distractor. The presence of the additional singleton was associated with slower behavioural responses to the shape target, and a greater neural signal in inferior frontal gyrus. To investigate the involvement of cognitive control functions of the frontal lobes in the capture of attention by the additional singletons, we measured the effect of the additional singleton in a context of either low or high working memory load. Whereas behavioural capture was unaffected by the level of load on working memory, greater activity associated with the presence of the additional singleton was observed in inferior frontal gyrus, but only under high load. This effect was greater in participants who experienced greater capture. We argue that the role of inferior frontal gyrus in selective attention is to detect potential sources of distraction.     

Gaze-fixation and pupil dilation in the processing of emotional faces: The role of rumination

Sustained attentional processing of negative information plays a significant role in the development and maintenance of depression. The present study examines the relationships between rumination, a relevant factor in information processing in depression, and the attentional mechanisms activated in individuals with different levels of depression severity when attending to emotional information (i.e., sad, angry and happy faces). Behavioural and physiological indicators of sustained processing were assessed in 126 participants (39 dysphoric and 87 non-dysphoric) using eye-tracking technology. Pupil dilation and total time attending to negative faces were correlated with a global ruminative style in the total sample once depression severity was controlled. Furthermore, in dysphoric participants the brooding component of rumination was specifically associated with the total time attending to sad faces. Finally, bootstrapping analyses showed that the relationships between global rumination and pupil diameter to emotional faces were accounted by total time attending to emotional faces, specifically for participants reporting lower levels of depression severity. The results support the idea that sustained processing of negative information is associated with a higher ruminative style and indicate differential associations between these factors at different levels of depressive symptomatology.     

Anxious mood narrows attention in feature space

Spatial attention can operate like a spotlight whose scope can vary depending on task demands. Emotional states contribute to the spatial extent of attentional selection, with the spotlight focused more narrowly during anxious moods and more broadly during happy moods. In addition to visual space, attention can also operate over features, and we show here that mood states may also influence attentional scope in feature space. After anxious or happy mood inductions, participants focused their attention to identify a central target while ignoring flanking items. Flankers were sometimes coloured differently than targets, so focusing attention on target colour should lead to relatively less interference. Compared to happy and neutral moods, when anxious, participants showed reduced interference when colour isolated targets from flankers, but showed more interference when flankers and targets were the same colour. This pattern reveals that the anxious mood caused these individuals to attend to the irrelevant feature in both cases, regardless of its benefit or detriment. In contrast, participants showed no effect of colour on interference when happy, suggesting that positive mood did not influence attention in feature space. These mood effects on feature-based attention provide a theoretical bridge between previous findings concerning spatial and conceptual attention.     

Proactive and reactive sequential effects on selective attention

Sequences of events can affect selective attention either through proactive mechanisms, through reactive mechanisms, or through a combination of the two. The current study examined electrophysiological responses to both prime and target stimuli in a primed dichotic listening task. Each trial presented a distractor prime syllable followed by two simultaneous syllables, and participants were asked to report one of the simultaneous syllables. Trials where the participant reported the non-primed syllable showed more negative event-related potentials at prime presentation, which may indicate inhibition of the prime representation. Trials where the participant reported the primed syllable showed more negative event-related potentials at target presentation, which may indicate cognitive conflict and effortful response selection. In context of current theories, the data suggest that the interplay of a proactive inhibition bias and a reactive potential for conflict is involved in causing sequential effects on selective attention mechanisms.     

How do students improve their value-based learning with task experience?

When learning items that vary in reward, students improve their scores (i.e., earned reward) with task experience. In four experiments, we examined whether such improvements arise from better selective encoding of items that would earn more (vs. less) reward. Participants studied and recalled words across multiple study-test trials. On each trial, 12 words were slated with different values (typically from 1 to 12), and participants earned the point value assigned to a given word if it was correctly recalled. In all experiments, participants earned more points across the first two trials. In Experiment 1, participants either self-paced their study or had experimenter-paced study and in Experiment 2, some participants were penalised for each second spent during study. Improvements in points earned were related to increases in overall recall but not to selective encoding. In Experiment 3, some participants were given value-emphasised instructions, yet they did not demonstrate selective encoding. In Experiment 4, we used a larger range of point values, but selective encoding still did not account for the improvement in point scores across lists. These results suggest that metacognitively-driven selective encoding is not necessary to observe improvements in value-based learning.     

Event familiarity influences memory detection using the aIAT

The developers of the autobiographical Implicit Association Test (aIAT) describe it as a possible memory detection tool. This claim rests on the assumption the aIAT can reliably and automatically detect the accuracy of autobiographical events. However, the aIAT may be susceptible to factors that affect the assessment of truth vs. falseness, such as the relative familiarity of those events. We compared aIAT performance when participants reported recent vs. childhood autobiographical events, and when participants imagined vs. did not imagine a fabricated autobiographical event. The aIAT was less effective at distinguishing between real and fabricated events from childhood, compared to recent real and fabricated events. Imagining a fabricated event did not affect aIAT performance; however, there was a trend in the data suggesting imagination may have reduced the effect of event recency. Our results provide further evidence that reducing or enhancing source confusion—via familiarity—can influence the predictive value of the aIAT.     

Stimulus-specific dynamics of learning in conjunction search tasks

We investigated the time course of learning in visual search for within-dimension conjunctions in homogeneous (inverted V in Vs) or heterogeneous distractors (L in 90° counterclockwise-rotated Ls and 180° rotated Ls), and for across-dimension conjunctions search (green\in green/s and red\s). Two learning sessions of 10 and 5 blocks each took place three months apart. In the first session, the reduction in mean search time was greater for within-dimension conjunctions with heterogeneous distractors. Learning endured from one session to the other for all stimuli, suggesting that learning can be long-term in search for feature conjunctions. However, when the positional regularity between elements was perturbed, the effect of prior learning was reduced for homogeneous within-dimension conjunctions. This suggests that, for these stimuli, learning facilitates grouping by positional regularity. Finally, the learning effect with homogeneous withindimension conjunctions disappeared when both target and distractors were rotated to modify the orientation of conjunction patterns. This suggests that learning improves a grouping mechanism selective for the relative orientations of combined form features.