Common items and reliability in personality measurement

Most psychological tests and inventories, particularly in personality and attitude measurement, contain common items, that is, various subscales of the test or inventory may share one or more items in common. Surprisingly, the role of common items in such a fundamental personality test attribute as reliability is not known. The present report specifically considered common-item contributions to test internal consistency reliability using extant data from the California Psychological Inventory. No negative contribution of item overlap was found. To the contrary, it was concluded that the use of common items is an economical technique for increasing the total number of items in the scales, thus increasing scale internal reliabilities without increasing the overall number of items in the inventory.     

A longitudinal study of the development of spatial conceptual ability

During October and November of 1983, three subsamples were selected from three schools in Mesa, Arizona: 34 students in 6th grade, 34 students in 8th grade, and 34 students in 10th grade. A battery of Piagetian-type tasks were individually and randomly administered to each subject. Seven tasks examined projective spatial conceptual abilities, and three tasks examined Euclidean abilities. The same battery of tasks was again administered to the same subjects during November and December of 1984 when all the subjects were in the next grade, that is, 7th, 9th, and 11th. Because of attrition, the number of students tested during the second year were 33, 30, and 28, respectively. To test for significant differences between grade levels, a chi-square one-sample procedure was used. Out of a possible 50 tasks, significant differences were detected in 36 (72%). Those findings, along with an examination of the percentage of students passing each task, support the notion of sequential development of spatial conceptual abilities.     

Semantic categorization in the human brain: spatiotemporal dynamics revealed by magnetoencephalography

We examined the cortical representation of semantic categorization using magnetic source imaging in a task that revealed both dissociations among superordinate categories and associations among different base-level concepts within these categories. Around 200 ms after stimulus onset, the spatiotemporal correlation of brain activity elicited by base-level concepts was greater within than across superordinate categories in the right temporal lobe. Unsupervised clustering of data showed similar categorization between 210 and 450 ms mainly in the left hemisphere. This pattern suggests that well-defined semantic categories are represented in spatially distinct, macroscopically separable neural networks, independent of physical stimulus properties. In contrast, a broader, task-required categorization (natural/man-made) was not evident in our data. The perceptual dynamics of the categorization process is initially evident in the extrastriate areas of the right hemisphere; this activation is followed by higher-level activity along the ventral processing stream, implicating primarily the left temporal lobe.     

Bimanual interference associated with the selection of target locations

Four experiments were conducted to identify the locus of interference observed during the preparation of bimanual reaching movements. Target locations were specified by color, and the right-hand and left-hand targets could be either the same or a different color. Movements of different amplitudes (Experiment 1) or different directions (Experiment 2) to targets of the same color were initiated more quickly than symmetric movements to targets of different colors. These results indicate that costs observed during bimanual movements arise during target selection rather than during motor programming. Experiments 3 and 4 further examined the interference associated with target selection. Reaction time costs were found with unimanual movements when the target was presented among distractors associated with responses for the other hand. Interference observed during bimanual reaching appears to reflect difficulty in segregating the response rules assigned to each hand.     

Some Legal Issues in Counselling and Psychotherapy

Although substantial legal difficulties can face anyone trying to recover compensation from counsellors for breach of their legal duties, such claims can in principle succeed. Counsellors ought to take particular care to provide a physically safe setting for the counselling session. Advice given to the client can lead to liability both to the client and to third parties who may be affected. The impact of the client's actions on third parties can justify, and less often compel, departures from confidentiality. The importance of keeping client records has to be balanced against legal obligations imposed on counsellors in various situations to make such records available for inspection by the client or third parties.     

Object-based representations govern both the storage of information in visual short-term memory and the retrieval of information from it

Interest is growing in how information is retained in visual short-term memory (VSTM). We describe an experiment that assesses VSTM within the context of multidimensional signal detection theory. On every trial, participants were presented with a 250-ms display containing four colored shapes. They were then probed 900 ms later with a colored shape and made separate old/new judgments about the color and the shape. In any particular trial, one, both, or neither of the probed features had been presented. Performance differed according to whether both probed features belonged to a single object or to two different objects. When both probed features belonged to the same object, featural retrieval was better than would be predicted by independent feature storage. When both probed features belonged to two different objects, featural retrieval was worse than would be predicted by independent feature storage. We conclude that storage in and retrieval from VSTM operate on the basis of object-based representations.     

Pupil diameter tracks changes in control state predicted by the adaptive gain theory of locus coeruleus function

An important dimension of cognitive control is the adaptive regulation of the balance between exploitation (pursuing known sources of reward) and exploration (seeking new ones) in response to changes in task utility. Recent studies have suggested that the locus coeruleus-norepinephrine system may play an important role in this function and that pupil diameter can be used to index locus coeruleus activity. On the basis of this, we reasoned that pupil diameter may correlate closely with control state and associated changes in behavior. Specifically, we predicted that increases in baseline pupil diameter would be associated with decreases in task utility and disengagement from the task (exploration), whereas reduced baseline diameter (but increases in task-evoked dilations) would be associated with task engagement (exploitation). Findings in three experiments were consistent with these predictions, suggesting that pupillometry may be useful as an index of both control state and, indirectly, locus coeruleus function.