Effects of Stimulus Number and Target-to-Distractor Ratio on the Performance of Random Array Letter Cancellation Tasks

Cancellation tests are commonly used in the clinical assessment of visuospatial function, but there has been little study of task characteristics influencing performance. This study was designed to assess factors which affect cancellation performance. Sixteen healthy subjects sequentially performed four random-array letter cancellation tasks. The forms contained 50 and 100 stimuli and target:distractor (T/D) ratios of 1:4 and 1:9 with target letter “A” and randomly selected letter distractors. The primary performance measure was calculated as the number of correctly cancelled targets divided by the time to complete the task, corrected for accuracy. This measure revealed a strong effect of T/D ratio (p< .0001), with performance adversely affected by higher proportion of distractors. There was no effect of stimulus number. This suggests that T/D ratio should be considered in cancellation test design and interpretation.     

The Convergent Validity of Four Burnout Measures in a Chinese Sample: A Confirmatory Factor‐Analytic Approach

The purpose of this paper is to study the convergent validity of the four most widely used burnout measures in a sample of Chinese nurses (N= 717). First, Structural Equation Modeling was used to investigate the factor structure of scores produced by the Maslach Burnout Inventory‐General Survey (MBI‐GS), the Burnout Measure (BM), the Shirom‐Melamed Burnout Measure (SMBM), and the Oldenburg Burnout Inventory (OLBI). Next, several competing models were tested to investigate the convergent validity of these four burnout instruments. The final results suggest that burnout is best conceived of as a multidimensional construct consisting of exhaustion and withdrawal, which are two related but conceptually distinct aspects. In addition, positively phrased items should be dropped from burnout measures for they constitute a separate factor that is considered to be an artifact.     

Perceptual learning in maze discriminations

In Experiment 1, rats were trained on a discrimination between rubber- and sandpaper-covered arms of a maze after one group had been pre-exposed to these intra-maze cues. Pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made easier by adding further discriminative stimuli, when it now significantly retarded learning. In Experiment 2, rats were trained on an extra-maze spatial discrimination, again after one group, but not another, had been pre-exposed to the extra-maze landmarks. Here too, pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made substantially easier by arranging that the two arms between which rats had to choose were always separated by 135°. The results of both experiments can be explained by supposing that perceptual learning depends on the presence of features common to S+ and S-.