Do you 'see' what I 'see'? Differentiation of visual action words.

Dickinson and Szeligo (Can J Exp Psychol 62(4):211-222, 2008) found that processing time for simple visual stimuli was affected by the visual action participants had been instructed to perform on these stimuli (e.g., see, distinguish). It was concluded that these effects reflected the differences in the durations of these various visual actions, and the results were compared to participants' subjective ratings of word meaning but it was also possible that word characteristics like length might have influenced response times. The present study takes advantage of word length differences between French and English visual action words in order to address this issue. The goals of the present study were to provide evidence that (1) the processing time differences previously found were due to differences in the cognitive actions represented by these words (and not due to characteristics to the words themselves), and (2) that individuals subjectively differentiate visual action words in such a way that allows for predictable differences in behaviour. Participants differentiated 14 French visual action words along two dimensions. Four of these words were then used in the instructions for a size-discrimination task. Processing time depended on the visual action word in the instruction to the task and differed in a predictable manner according to word meaning but not word length.

Impact of mental operation instructions.

Experiments were conducted to test the impact of embedding mental action verbs within instructions. Experiment 1 examined the instructional effects of these verbs on response time to a visual stimulus. Significant response time differences resulted from instructing participants to engage in different mental actions. Using Multidimensional Scaling, Experiment 2 explored how people understand the relationships amongst mental action verbs, resulting in a single "level of processing" dimension. Experiment 3 was designed to further explore the relationship of these verbs to cognition and behaviour. Signal detection analysis was used to determine if participants were shifting their criterion depending on the level of processing suggested in the instruction. Results showed an effect of instruction on response time, but not on criterion, sensitivity, or accuracy. Response time effects were found that were consistent with differences in word characteristics, including meaning.

Dichotic target detection with words: a modified procedure.

The purpose of the present study was to investigate the influence of attention on the magnitude and reliability of laterality effects in dichotic target detection. Twenty-five participants completed a dichotic target detection task requiring them to identify the ear to which a target word was presented. Correct left and right responses (LL and RR outcomes, respectively) produced a large and reliable right ear advantage (REA). Participants circled right when the target was presented to the left ear (LR outcomes) more often than they circled left when the target was presented to the right (RL outcomes). A combination of the LL+LR outcomes compared to RR+RL outcomes resulted in a reduced REA. Finally, cases where participants incorrectly responded left or right when the target was absent produced no systematic differences, reflecting the absence of a generalized bias to respond "right." The discussion emphasizes the usefulness of the approach presented here in producing a score that minimizes the attentional component of laterality effects.

Adaptations of writing posture in response to task demands for left- and right-handers.

Handedness and writing posture are visible manifestations of differences between left- and right-handers. Although an inverted posture is witnessed in both groups, there is a much higher proportion of left-handers who invert. This study is framed within the adaptation hypothesis of writing posture, which states that invertedness in left-handers develops in response to the demands of cursive writing. Participants (N = 57) comprising left-handed inverters, left-handed standard writers, and right-handed standard writers engaged in tasks that required them to form letters and pen strokes at extreme angles. In addition participants were questioned about attempts to change writing posture. We hypothesised that letter angle controls posture in both left- and right-handers and that inverted posture would be a target of intervention. The results of the study showed some support for these hypotheses in that left- and right-handers adapted their posture in response to the constraints placed upon them and inverters reported more intervention.

Mechanisms of dressing apraxia: a case study.

OBJECTIVE: To investigate the neural mechanisms that differentiate dressing apraxia from other forms of apraxia such as ideomotor apraxia. Hypotheses examined included (1) that dressing is more sensitive to alternations in body schema, (2) that dressing is a demanding bimanual task, and (3) that clothing represents a particularly complex spatial problem. BACKGROUND: A focal degenerative condition can specifically target a function such as dressing, allowing a unique approach to its study. METHOD: A case study of the cognitive impairments of a 75-year-old man who presented with progressive dressing difficulties in the absence of neglect or motor disturbances. RESULTS: Neuropsychologic testing indicated possible executive function deficits as well as visuospatial and visuocontructional deficits, but intact praxic skills, verbal abilities, and visual recognition skills. In addition, testing revealed no evidence of Balint's or impairments in body schema. CONCLUSION: Overall, the test results suggested that visuospatial dysfunction is the underlying deficit in dressing apraxia. The present case study confirmed the independence of praxic functioning from spatial ability and conversely, the dependence of dressing on spatial ability.