A neurally plausible parallel distributed processing model of event-related potential word reading data

The Parallel Distributed Processing (PDP) framework has significant potential for producing models of cognitive tasks that approximate how the brain performs the same tasks. To date, however, there has been relatively little contact between PDP modeling and data from cognitive neuroscience. In an attempt to advance the relationship between explicit, computational models and physiological data collected during the performance of cognitive tasks, we developed a PDP model of visual word recognition which simulates key results from the ERP reading literature, while simultaneously being able to successfully perform lexical decision—a benchmark task for reading models. Simulations reveal that the model’s success depends on the implementation of several neurally plausible features in its architecture which are sufficiently domain-general to be relevant to cognitive modeling more generally.     

Mighty metaphors: behavioral and ERP evidence that power shifts attention on a vertical dimension

Thinking about the abstract concept power may automatically activate the spatial up-down image schema (powerful up; powerless down) and consequently direct spatial attention to the image schema-congruent location. Participants indicated whether a word represented a powerful or powerless person (e.g. ‘king’ or ‘servant’). Following each decision, they identified a target at the top or bottom of the visual field. In Experiment 1 participants identified the target faster when their spatial position was congruent with the perceived power of the preceding word than when it was incongruent. In Experiment 2 ERPs showed a higher N1 amplitude for congruent spatial positions. These results support the view that attention is driven to the image schema congruent location of a power word. Thus, power is partially understood in terms of vertical space, which demonstrates that abstract concepts are grounded in sensory-motor processing.     

The brain's hemispheres and controlled search of the lexicon: evidence from fixated words and pseudowords

Difference between the brain's hemispheres in efficiency of intentional search of the mental lexicon with phonological, orthographic, and semantic strategies was investigated. Letter strings for lexical decision were presented at fixation, with a lateralized distractor to the LVF or RVF. Word results revealed that both hemispheres were capable of using each of the three strategies, but the right hemisphere had better baseline processing of orthography and was better at processing semantics. Pseudoword results supported the right hemisphere advantage for orthography and showed a left hemisphere advantage for phonology and assessment of possible semantic relationships. Taken together, the data support the idea that the right hemisphere uses orthography to make efficient decisions about novelty of an item, while the left engages in grapheme-to-phoneme conversion to test hypotheses about unfamiliar items. The convergence of data with previous research reveals that the procedure, as well as analyses of pseudowords, inform laterality research.     

Brain activation during spatial updating and attentive tracking of moving targets

Keeping aware of the locations of objects while one is moving requires the updating of spatial representations. As long as the objects are visible, attentional tracking is sufficient, but knowing where objects out of view went in relation to one's own body involves an updating of spatial working memory. Here, multiple object tracking was employed to study spatial updating and its neural correlates. In a dynamic 3D-scene, targets moved among visually indistinguishable distractors. The targets and distractors either stayed visible during continuous viewpoint changes or they turned invisible. The parametric variation of tracking load revealed load-dependent activations of the intraparietal sulcus, the superior parietal lobule, and the lateral occipital cortex in response to the attentive tracking task. Viewpoint changes with invisible objects that demanded retention and updating produced load-dependent activation only in the precuneus in line with its presumed involvement in updating spatial working memory.     

Developmental change in young children's use of haptic information in a visual task: the role of hand movements

Preschoolers who explore objects haptically often fail to recognize those objects in subsequent visual tests. This suggests that children may represent qualitatively different information in vision and haptics and/or that children’s haptic perception may be poor. In this study, 72 children (2½-5 years of age) and 20 adults explored unfamiliar objects either haptically or visually and then chose a visual match from among three test objects, each matching the exemplar on one perceptual dimension. All age groups chose shape-based matches after visual exploration. Both 5-year-olds and adults also chose shape-based matches after haptic exploration, but younger children did not match consistently in this condition. Certain hand movements performed by children during haptic exploration reliably predicted shape-based matches but occurred at very low frequencies. Thus, younger children’s difficulties with haptic-to-visual information transfer appeared to stem from their failure to use their hands to obtain reliable haptic information about objects.     

We're all in this together now: group performance feedback to increase classroom team data collection

This study's primary goal was to evaluate the use of performance feedback procedures delivered to a classroom team to increase daily data collection. Performance feedback (PFB) was delivered to four classroom teams responsible for the daily collection of data representing student performance during prescribed instructional activities. Using a multiple-baseline design, the effects of the team performance-feedback were evaluated for the target student, and for generalization to data collection for all classroom students. A secondary question evaluated if student on-task behavior correlated with increased data collection. Finally, social validity was investigated to evaluate team satisfaction with the PFB intervention. The results demonstrate improved data collection across all four classroom teams for the target student in each classroom and generalization within classrooms to all remaining students. Slight increases in student on-task behavior were observed in three of the four classrooms, and teacher satisfaction ratings were high.     

The role of the human extrastriate visual cortex in mirror symmetry discrimination: a TMS-adaptation study

The human visual system is able to efficiently extract symmetry information from the visual environment. Prior neuroimaging evidence has revealed symmetry-preferring neuronal representations in the dorsolateral extrastriate visual cortex; the objective of the present study was to investigate the necessity of these representations in symmetry discrimination. This was accomplished by the use of state-dependent transcranial magnetic stimulation, which combines the fine resolution of adaptation paradigms with the assessment of causality. Subjects were presented with adapters and targets consisting of dot configurations that could be symmetric along either the vertical or horizontal axis (or they could be non-symmetric), and they were asked to perform a symmetry discrimination task on the targets while fixating the center of the screen. TMS was applied during the delay between the adapter and the test stimulus over one of four different sites: Left or Right V1/V2, or left or right dorsolateral extrastriate cortex (DLO). TMS over both Left and Right DLO reduced the adaptation effect in detecting vertical and horizontal symmetry, although the Left DLO effect on horizontal symmetry and the Right DLO effect on both vertical and horizontal symmetry were present only when considering subjects who showed a behavioral adaptation effect in the baseline No-TMS condition. Application of TMS over the Left or Right V1/V2 did not modulate the adaptation effect. Overall, these data suggest that both the Left and Right DLO contain neuronal representations tuned to mirror symmetry which play a causal role in symmetry discrimination.     

Does degree of asymmetry relate to performance? A reply to Boles and Barth

In a recent critique Boles and Barth (2011) argue that their prior study investigating asymmetry/performance relationships (Boles, Barth, & Merrill, 2008) uncovered the “true” association (i.e., negative correlation) between lateralization of visual lexical processes and word recognition performance. They contend that our study reporting positive correlations of lexical asymmetry and reading performance (Chiarello et al., 2009) was flawed and hence inconclusive. In this response we address the two major objections raised by Boles and Barth (2011) regarding our selection of tasks and asymmetry measures. We conclude that the Boles and Barth principle of task purity is not relevant to the stated aims of our investigation, and that our linear regression method of measuring asymmetry is valid given the high level of accuracy for the tasks we reported. Because the aims of each investigation differed, we argue that it is unwise to attempt to fit each study into the framework favored by Boles and Barth (2011).     

How emotional pictures influence visuospatial binding in short-term memory in ageing and Alzheimer’s disease?

The present study examines the prediction that emotion can facilitate short-term memory. Nevertheless, emotion also recruits attention to process information, thereby disrupting short-term memory when tasks involve high attentional resources. In this way, we aimed to determine whether there is a differential influence of emotional information on short-term memory in ageing and Alzheimer's disease (AD). Fourteen patients with mild AD, 14 healthy older participants (NC), and 14 younger adults (YA) performed two tasks. In the first task, involving visual short-term memory, participants were asked to remember a picture among four different pictures (negative or neutral) following a brief delay. The second task, a binding memory task, required the recognition by participants of a picture according to its spatial location. The attentional cost involved was higher than for the first task. The pattern of results showed that visual memory performance was better for negative stimuli than for neutral ones, irrespective of the group. In contrast, binding memory performance was essentially poorer for the location of negative pictures in the NC group, and for the location of both negative and neutral stimuli in the AD group, in comparison to the YA group. Taken together, these results show that emotion has beneficial effects on visual short-term memory in ageing and AD. In contrast, emotion does not improve their performances in the binding condition.     

Asymmetrical brain activity induced by voluntary spatial attention depends on the visual hemifield: a functional near-infrared spectroscopy study

The effect of the visual hemifield to which spatial attention was oriented on the activities of the posterior parietal and occipital visual cortices was examined using functional near-infrared spectroscopy in order to investigate the neural substrates of voluntary visuospatial attention. Our brain imaging data support the theory put forth in a previous psychophysical study, namely, the attentional resources for the left and right visual hemifields are distinct. Increasing the attentional load asymmetrically increased the brain activity. Increase in attentional load produced a greater increase in brain activity in the case of the left visual hemifield than in the case of the right visual hemifield. This asymmetry was observed in all the examined brain areas, including the right and left occipital and parietal cortices. These results suggest the existence of asymmetrical inhibitory interactions between the hemispheres and the presence of an extensive inhibitory network.