A constraint on comparisons: Equally detailed alternatives

Children's errors in collective comparison tasks are atributed to the comparison of the wrong classes. It is specifically hypothesized that alternative classes are erroneously formed subject to the constrain that the same kinds of properties are criterial for each alternative. This hypothesis, called the equally detailed alternatives hypothesis, is tested in three experiments with hierarchically organized stimuli and requests to compare a superordinate class and a nonincluded subclass, for example, dogs and yellow cats. In all three experiments 4-year-old children's comparisons were found to be in accord with the hypothesis. In the first experiment both perceptual and linguistic factors determine which classes are compared. In the second experiment, as predicted, erroneous subclass comparisons were more common when all subclasses were distinguished by the same kinds of properties. In the third experiment, the children were asked to partition the stimulus objects into the classes to be compared. The vast majority of partitions were erroneous and in accord with the hypothesis. Potential benefits of the constrain are considered.     

THE RELATION BETWEEN CHOOSING AND WORKING PREVOCATIONAL TASKS IN TWO SEVERELY RETARDED YOUNG ADULTS

This study investigated the relation between prevocational preference, as measured by the client's selection of a task object, and the work that followed that choice. After selecting a task object, the clients worked a task previously assessed to be more or less preferred than the one indicated by the object. The results indicated that when the selection represented a task that was less preferred than the one actually worked, choices for that object increased on subsequent trials. Conversely, when the selection represented a task that was more preferred than the task subject actually worked, choices for the object decreased on subsequent trials. The work that followed object choices reinforced or punished subsequent selections. These findings indicated that the clients' object choices were valid indicators of their preference for working different tasks. They were also consistent with Premack's principle that one class of responses may reinforce or punish a different class of responses for the same individual.     

Prenatal cortisol, prematurity and low birthweight

Three hundred depressed pregnant women were recruited at approximately 20 weeks gestation. They were then divided by a median split into high and low urinary cortisol level groups. The high cortisol group had higher CES-D depression scores and higher inhibition (BIS) scores prenatally. Their fetuses had smaller head circumference, abdominal circumference, biparietal diameter and fetal weight. The high cortisol group neonates were shorter gestational age and lower birthweight and they had lower Brazelton habituation and higher Brazelton reflex scores. Discriminant function analyses suggested that cortisol levels more accurately classified short gestation and low birthweight groups than CES-D depression scores.     

Effects of stress and sex on acquisition and consolidation of human fear conditioning

We examined the relationship between stress hormone (cortisol) release and acquisition and consolidation of conditioned fear learning in healthy adults. Participants underwent acquisition of differential fear conditioning, and consolidation was assessed in a 24-h delayed extinction test. The acquisition phase was immediately followed by an 11-min psychosocial stress period (arithmetic test combined with a public speech). Salivary cortisol was sampled at various time points before and after acquisition and retention of fear conditioning. Results showed two effects of endogenous cortisol. Post-acquisition cortisol correlated with fear acquisition in male but not female participants. In addition, post-acquisition cortisol correlated with consolidation of fear but only in those participants with high cortisol levels. We conclude that in the short term, a robust and sexually dimorphic relationship exists between fear learning and stress hormone levels. For those participants whose fear learning is accompanied by high stress hormone levels, a long-term relationship exists between cortisol release and memory consolidation. These short-term and long-term effects may relate to the differential involvement of mineralocorticoid and glucocorticoid receptor subtypes, respectively. The findings have implications for understanding the role of stress, sex, and hormones in different stages of fear learning and memory.     

Accounting for cognitive aging: context processing, inhibition or processing speed?

Age-related deficits in context processing were examined in relationship to two predominant theories of cognitive aging (the Inhibitory Deficit and Processing Speed Models). Older and younger adults completed a measure of context processing (AX Continuous Performance Test (CPT) task) as well as a computerized battery of inhibitory tasks: Stroop, garden path sentences, go no-go, and the stop-signal paradigm. Participants also completed a simple processing speed task. After controlling for baseline differences in processing speed, age effects were detected on the AX-CPT. Smaller, but significant age effects were noted on the Stroop and stop-signal tasks, but no significant age effects were found on the garden path sentence and go no-go tasks. Intertask correlations were weak, providing little evidence for a homogenous or uniform construct of inhibition. The sensitivity of the AX-CPT to cognitive aging is discussed in the context of existing theories of cognitive aging. The authors suggest that deficits in context processing and utilization may underlie cognitive aging phenomena.     

Easier tasks can have better discriminating power: the case of verbal fluency

Loren and Jean Chapman highlighted the importance that the psychometric characteristics of a task may have when comparing different populations (L. J. Chapman & J. P. Chapman, 1973, 1978). Specifically, they pointed out that when comparing 2 tasks measuring different constructs, there is a greater likelihood of finding larger deficits on a task with higher discriminating power, irrespective of what the task measures. While researchers have addressed this issue, they typically have assumed that more difficult tasks have greater discriminating power, often without actually measuring discriminating power. In this article, the authors present data from 2 studies using phonologic and category fluency tasks to demonstrate that the critical factor for task selection and matching is discriminating power, not task difficulty.     

Schedule thinning following communication training: using competing stimuli to enhance tolerance to decrements in reinforcer density

Functional communication training (FCT) is a widely used treatment for individuals with developmental disabilities who exhibit severe behavior problems. One inherent challenge of employing FCT as a treatment in the community is that reinforcement for appropriate communication cannot always be immediate or even possible in some circumstances. Of the few studies that have incorporated some form of schedule thinning for communication, most have reported disruption of communication or increases in problem behavior when the schedule of reinforcement is thinned. In the current study, we compared FCT with extinction to FCT with extinction and access to competing stimuli. After conducting a functional analysis, a competing stimulus assessment was performed to identify stimuli that produce reinforcement that ostensibly competes with reinforcement that maintains problem behavior. It was hypothesized that FCT with competing stimuli would result in more stable reductions in problem behavior during schedule thinning, which would ultimately result in quicker achievement of the treatment goal (low levels of problem behavior under the terminal reinforcement schedule for communication) than FCT without competing stimuli. Results confirmed this hypothesis.     

Context processing and context maintenance in healthy aging and early stage dementia of the Alzheimer's type

Declines in the ability to process context information may represent a fundamental mechanism of age-related cognitive changes. Two components of context processing--activation/updating and maintenance--were examined in a sample of healthy younger and older adults, along with individuals suffering from early stage dementia of the Alzheimer's type (DAT). All older adult groups showed context activation/updating impairments, whereas context maintenance was only impaired in the oldest adults (age>75 years) and was further exacerbated in DAT individuals. The results suggest that context processing may be composed of functionally dissociable components and point to the utility of this construct in understanding the timecourse of cognitive decline in healthy and pathological aging.     

EFFECTS OF EVIDENCE ON ATTITUDES:

Abstract— A 1979 study by Lord, Ross, and Lepper has been widely cited as showing that examination of mixed evidence on a topic leads to polarization of altitudes The polarization phenomenon, we suggest, in fact encompasses two distinct change patterns—a shift from an initially moderate to a more extreme position (regarded here as genuine polarization) and a shift from an initially neutral to a moderate position (which might better be termed "articulating a position") The findings reported here indicate that genuine polarization is a real but infrequent outcome of exposure to mixed evidence In addition, we offer data in support of the view that the effective component of such interventions is simply cognitive engagement, rather than exposure to new evidence.