Qualitative block design analysis in posttraumatic stress disorder

Qualitative and quantitative Block Design performance was examined in Vietnam combat veterans with PTSD diagnoses (n = 23) and Vietnam combat veterans without PTSD or other mental disorders diagnoses (n = 19). Results indicated that PTSD-diagnosed veterans committed more single block rotations than the comparison sample, and that their errors occurred more frequently in right hemispace than errors made by the comparison sample. The two groups did not differ in the number of configural errors made, errors committed in left hemispace, or in quantitative performance measures. Findings are suggestive of relative left hemisphere hypoactivation and are congruent with prior research documenting cerebral asymmetries in emotional disorders.     

An individual differences analysis of ability and strategy influences: age-related differences in associative learning

The relationships among abilities, strategies, and performance on an associative learning task were investigated for young (aged 17 to 34) and older adults (aged 60 to 82). Participants received extensive practice on a noun-pair task in which they could use a visual-scanning strategy or a memory-retrieval strategy. Older adults were more likely to use the scanning strategy. Age differences were reduced when comparisons were made only for participants using a retrieval strategy. Associative memory was predictive of learning on the task, and semantic memory access speed was predictive of practiced performance. Practiced performance on a memory-search task that also required associative learning was predictive of practiced noun-pair performance. Models of ability-performance relationships for skill acquisition are discussed.     

How do speakers avoid ambiguous linguistic expressions?

Three experiments assessed how speakers avoid linguistically and nonlinguistically ambiguous expressions. Speakers described target objects (a flying mammal, bat) in contexts including foil objects that caused linguistic (a baseball bat) and nonlinguistic (a larger flying mammal) ambiguity. Speakers sometimes avoided linguistic-ambiguity, and they did so equally regardless of whether they also were about to describe foils. This suggests that comprehension processes can sometimes detect linguistic-ambiguity before producing it. However, once produced, speakers consistently avoided using the same linguistically ambiguous expression again for a different meaning. This suggests that production processes can successfully detect linguistic-ambiguity after-the-fact. Speakers almost always avoided nonlinguistic-ambiguity. Thus, production processes are especially sensitive to nonlinguistic- but not linguistic-ambiguity, with the latter avoided consistently only once it is already articulated.     

Straightness as a cue for luminance edge interpretation

In order to determine the reflectance of a surface, it is necessary to discount luminance changes produced by illumination variation, a process that requires the visual system to respond differently to luminance changes that are due to illumination and reflectance. It is known that various cues can be used in this process. By measuring the strength of lightness illusions, we find evidence that straightness is, used as a cue: When a boundary is straight rather than curved, it has a greater tendency to be discounted, as if it were an illumination edge. The strongest illusions occur when a boundary has high contrast and has multiple X-junctions that preserve a consistent contrast ratio.     

Comparing performance by parents and offspring on a rapid tapping task

The purpose of this study was to identify the relationships between 42 parents' and their offsprings' performance on a rapid tapping task. It was expected that genetic predispositions would gradually limit children's performance on a tapping task as they matured chronologically. Four different age groups of children and their parents performed the tapping task on different sizes of boards. Repeated-measures analysis of variance indicated that, while parents' mean performance was generally higher than that of their children (F = 32.89, p < .001), the difference was affected by the children's age, which hand was used, and the board size. Spearman rank correlation scores between parents' and children's overall performances gradually increased across age groups (p = -.29, -.10, .47, and .40, respectively, from younger to older age groups). This finding suggests that the potential of youngsters' future performance may be predicted with greater certainty by observing their parents' present performance. This may improve the predictive power of planned programs.     

Influence of multiple categories on the prediction of unknown properties

Knowing an item's category helps us predict its unknown properties. Previous studies suggest that when asked to evaluate the probability of an unknown property, people tend to consider only an item's most likely category, ignoring alternative categories. In the present study, property prediction took the form of either a probability rating or a speeded binary-choice judgment. In keeping with past findings, the subjects ignored alternative categories in their probability ratings. However, their binary-choice judgments were influenced by alternative categories. This novel finding suggests that the way in which category knowledge is used in prediction depends critically on the form of the prediction.     

Premovement activity of the pre-supplementary motor area and the readiness for action: studies of time-resolved event-related functional MRI

The supplementary motor area (SMA) is thought to play in important role in the preparation and organisation of voluntary movement. It has long been known that cortical activity begins to increase up to 2s prior to voluntary self-initiated movement. This increasing premovement activity measured in EEG is known as the Bereitschaftspotential or readiness potential. Modern functional brain imaging methods, using event-related and time-resolved functional MRI techniques, are beginning to reveal the role of the SMA, and in particular the more anterior pre-SMA, in premovement activity associated with the readiness for action. In this paper we review recent studies using event-related time-resolved fMRI methods to examine the time-course of activation changes within the SMA throughout the preparation, readiness and execution of action. These studies suggest that the pre-SMA plays a common role in encoding or representing actions prior to our own voluntary self-initiated movements, during motor imagery, and from the observation of others' actions. We suggest that the pre-SMA generates and encodes motor representations which are then maintained in readiness for action.     

Developmental regression in autism spectrum disorders

The occurrence of developmental regression in autism is one of the more puzzling features of this disorder. Although several studies have documented the validity of parental reports of regression using home videos, accumulating data suggest that most children who demonstrate regression also demonstrated previous, subtle, developmental differences. Counter to clinical intuition, the earlier development of social, language, and attachment behaviors followed by regression does not seem to support later recovery of skills or better developmental outcomes compared to children who never had speech or typical social responsivity. In fact, this regressive group may have somewhat greater developmental impairment than the nonregressive group, though the two groups do not appear to present different behavioral phenotypes. Although autism is not the only condition in which regression occurs, it appears to be the most frequent condition. Other disorders that demonstrate an early regression with no known etiology include total blindness from birth and childhood disintegrative disorder, both of which demonstrate behavioral relations to autism. In addition, two biological conditions with known etiologies also involve regression with some behaviors resembling autism behavioral phenotype: Rett syndrome (a genetic disorder; see Glaze, this issue) and Landau-Kleffner syndrome (see McVicar and Shinnar, this issue), which involves a seizure disorder.