Context-outcome associations mediate context-switch effects in a human predictive learning task

Four experiments explored the role of contexts in information retrieval after different levels of acquisition training in human predictive learning. Participants were trained where cue (X) was followed by an outcome in context A while a different cue (Y) was followed by the absence of the outcome in context B. When 4 training trials with each cue were conducted, testing the stimuli in the alternative contexts decreased predictive judgments to X and increased predictive judgments to Y. These effects disappeared both when training was increased up to 18 trials (Experiments 1a and 1b), and when the outcome was presented in both contexts A and B (Experiments 2 and 4). When the outcome was presented in both contexts, the nonreinforced cue Y, trained in the presumably excitatory context B, became a conditioned inhibitor (Experiment 3). Additional experience with one of the contexts, but not with both, made the context-switch effect reappear (Experiment 4). These results suggest that irrelevant contexts may enter into direct associations with the outcome before prolonged training leads participants to discard them as predictors.     

Why are auditory novels distracting? Contrasting the roles of novelty, violation of expectation and stimulus change

Past studies show that novel auditory stimuli, presented in the context of an otherwise repeated sound, capture participants’ attention away from a focal task, resulting in measurable behavioral distraction. Novel sounds are traditionally defined as rare and unexpected but past studies have not sought to disentangle these concepts directly. Using a cross-modal oddball task, we contrasted these aspects orthogonally by manipulating the base rate and conditional probabilities of sound events. We report for the first time that behavioral distraction does not result from a sound’s novelty per se but from the violation of the cognitive system’s expectation based on the learning of conditional probabilities and, to some extent, the occurrence of a perceptual change from one sound to another.     

Impairments in tactile search following superior parietal damage

The superior parietal cortex is critical for the control of visually guided actions. Research suggests that visual stimuli relevant to actions are preferentially processed when they are in peripersonal space. One recent study demonstrated that visually guided movements towards the body were more impaired in a patient with damage to superior parietal cortex. Whereas past studies have explored disordered movement in optic ataxic patients, there has been less exploration of space perception in terms of search capacity in this population. In addition, there is some debate concerning the relationship between deficits of visuomotor control and impaired attention/perception in optic ataxia. Given that the dorsal stream has been implicated in the spatial processing of stimuli in peripersonal space, and damage to this region is known to cause optic ataxia, we felt that further investigation was warranted. We examined tactile search behavior in the fronto-parallel and radial planes in a patient with right superior parietal damage and optic ataxia. We used a pegboard with removable cylindrical pegs that allowed for the reorganization of targets between trials. To better characterize three-dimensional search behavior, we included both horizontal and vertical search conditions. Results showed that the patient spent more time searching, was more accurate and revisited more targets in right versus left space. Interestingly, the patient spent the majority of her time specifically searching the lower right quadrant of the stimulus array. Further analysis revealed lower target detection rates along the outer borders of the pegboard on all sides. The search pattern observed here is unusual considering that all targets were within arm's reach. The present experiment demonstrates that damage to superior parietal cortex impairs tactile search and biases exploration towards lower right peripersonal space.     

9 is always on top: assessing the automaticity of synaesthetic number-forms

For number-form synaesthetes, digits occupy idiosyncratic spatial locations. Atypical to the mental number line that extends horizontally, the synaesthete (L) experiences the numbers 1-10 vertically. We used a spatial cueing task to demonstrate that L’s attention could be automatically directed to locations within her number-space - being faster to detect targets appearing in synaesthetically cued locations. We sought to eliminate any influence of strategy on L’s performance by: (a) shortening the cue-target onset to 150 ms, (b) making the cues counterpredictive, and (c) instructing L to use an opposing strategy. If L’s performance was attributable to intentionally using the cue to predict target location, these manipulations should eliminate any cuing effects consistent with her synaesthesia. However, L showed an attentional bias compatible with her number-form, except when explicitly instructed of the opposing strategy and given enough time (800 ms). Therefore, we attribute L’s resilient cueing effects to the automaticity of her number-form.     

Age-related differences in attentional networks of alerting and executive control in young, middle-aged, and older Chinese adults

Previous studies suggest that aging is associated with impairment of attention. However, it is not known whether this represents a global attentional deficit or relates to a specific attentional network. We used the attention network test to examine three groups of younger, middle-aged, and older participants with respect to the efficiency of three anatomically defined attentional networks: alerting network, orienting network, and executive control network. Age-related change was found to have the greatest effect on the executive network and the least effect on the alerting network as well as on overall mean response time. Impairment of the orienting network was found to be insignificant. Age-related deterioration of the prefrontal lobe, the dopaminergic system, and function of specific genes may explain the age-related changes in executive attention, which occur after the fourth decade of life.     

Effects of attention on dichotic listening in elderly and patients with dementia of the Alzheimer type

This article presents an overview of our studies in elderly and Alzheimer patients employing Kimura's dichotic digits paradigm as a measure for left hemispheric predominance for processing language stimuli. In addition to structural brain mechanisms, we demonstrated that attention modulates the direction and degree of ear asymmetry in dichotic listening. Elderly showed increasingly more difficulties focusing attention on the left ear (LE) with advancing age. Alzheimer patients showed severe deficits to allocate attention to the LE, which could result in a right ear advantage. These results may be attributed to a breakdown of the cortical attentional network which is mediated by frontal (inhibitory control of attention) and parietal regions (spatial attention and 'disengagement processes'). Both interhemispheric disconnectivity (callosal atrophy) and intrahemispheric disconnectivity (subcortical white matter lesions) appear to be important factors contributing to these findings.     

Attention and the right-ear advantage: What is the connection?

Dichotic listening originally was a means of studying attention. Half a century ago Doreen Kimura parlayed the dichotic method into a noninvasive indicator of lateralized cerebral language representation. The ubiquitous right-ear advantage (REA) for verbal material was accepted as a concomitant of left-sided language lateralization and preferential conduction of right-ear messages to the left hemisphere. As evidence has accumulated over the past 50years showing the REA to be dynamic and modifiable, the concept of attention has become essential for interpreting the findings. Progress in understanding the role of attention has been manifested as a transition from efforts to document attention effects to efforts to characterize their mechanisms. We summarize the relevant evidence, trace the evolution of explanatory models, and outline contemporary accounts of the role of attention in dichotic listening.     

Individual differences in cognitive-flexibility: the influence of spontaneous eyeblink rate, trait psychoticism and working memory on attentional set-shifting

Individual differences in psychophysiological function have been shown to influence the balance between flexibility and distractibility during attentional set-shifting [e.g., Dreisbach et al. (2005). Dopamine and cognitive control: The influence of spontaneous eyeblink rate and dopamine gene polymorphisms on perseveration and distractibility. Behavioral Neuroscience, 119(2), 483-490]. Here we replicate both the facilitatory and detrimental influence of spontaneous eyeblink rate upon switch costs across the two distinct conditions of a set-shifting task. We extend this by presenting additional, putatively dopamine related, individual differences that also influence attentional control. Whereas trait psychoticism showed a pattern of effects opposite to that of eyeblink rate, greater working memory served to decrease switch costs across both conditions. These results highlight the need for further exploration of the role of dopaminergic neurotransmission and component processes involved in such attentional paradigms, and illustrates the importance of considering individual differences in cognitive control.     

Proneness for psychological flow in everyday life: Associations with personality and intelligence

Flow is an experience of enjoyment, concentration, and low self-awareness that occurs during active task performance. We investigated associations between the tendency to experience flow (flow proneness), Big Five personality traits and intelligence in two samples. We hypothesized a negative relation between flow proneness and neuroticism, since negative affect could interfere with the affective component of flow. Secondly, since sustained attention is a component of flow, we tested whether flow proneness is positively related to intelligence. Sample 1 included 137 individuals who completed tests for flow proneness, intelligence, and Big Five personality. In Sample 2 (all twins; n = 2539), flow proneness and intelligence, but not personality, were measured. As hypothesized, we found a negative correlation between flow proneness and neuroticism in Sample 1. Additional exploratory analyses revealed a positive association between flow proneness and conscientiousness. There was no correlation between flow proneness and intelligence. Although significant for some comparisons, associations between intelligence and flow proneness were also very weak in Sample 2. We conclude that flow proneness is associated with personality rather than intelligence, and discuss that flow may be a state of effortless attention that relies on different mechanisms from those involved in attention during mental effort.     

Spatial probability cuing and right hemisphere damage

In this experiment we studied statistical learning, inter-trial priming, and visual attention. We assessed healthy controls and right brain damaged (RBD) patients with and without neglect, on a simple visual discrimination task designed to measure priming effects and probability learning. All participants showed a preserved priming effect for item color. Contrary to healthy controls and RBD participants without neglect, RBD participants with neglect did not show positional priming and both RBD groups learned the underlying spatial probability distribution of target locations to a lesser degree. To see if the latter deficiency could be improved, we tested a patient with long standing chronic spatial neglect on three separate days and observed improved identification times for left sided, high probability, targets. In summary, we found preservation of priming per se in people with spatial neglect. However, this was only clearly demonstrable for color priming and not for positional priming. Associated with this impairment was a difficulty in learning the overall statistical structure of target locations. In a patient with severe persistent neglect we were able to demonstrate that the deficit in statistical learning was not absolute, as this subject improved his identification times for targets appearing in high probability regions of the test display.