Aging and the psychological refractory period: task-coordination strategies in young and old adults

The apparently deleterious effect of aging on dual-task performance is well established, but there is little agreement about the source of this effect. Studies of the psychological refractory period (PRP) indicate that young adults can flexibly control dual-task performance through task-coordination strategies. Thus, the performance of older adults might differ from young adults because older adults use different task-coordination strategies. To test this hypothesis, the executive-process interactive control (EPIC) architecture was applied to quantify the reaction time data from two PRP experiments conducted with young (age 18-26) and older (age 60-70) adults. The results show that participants' ability to coordinate the processing of two tasks did not decline with age. However, dual-task time costs were greater in the older adults. Three sources for this increase were found: generalized slowing, process-specific slowing, and the use of more cautious task-coordination strategies by the older adults.     

Psychophysiologic correlates of Type A behavior: Comments on Houston (1983) and Holmes (1983)

On the basis of a literature review, B. K. Houston (1983, Journal of Research in Personality, 17, 22–39) concluded that there is a reliable but relatively weak association between Type A (coronary-prone) behavior and heightened physiologic reactivity. D. S. Holmes (1983, Journal of Research in Personality, 17, 40–47) contends that by failing to take into account dependent measures yielding null results, Houston overestimated the consistency with which A/B differences have been obtained. In the present article, we show that it is critical to take into account the method used to assess Type A behavior. Structured Interview assessments show a more consistent association with reactivity than those based on the Jenkins Activity Survey. We then point out that, for certain physiologic measures, null effects do not necessarily reflect an absence of A/B differences in sympathetic-adrenomedullary activity. Other issues that are discussed include the role of situational parameters in eliciting hyperresponsiveness in Type A's, the problem of evaluating the magnitude and importance of A/B effects, and the need for a more theoretical approach to the study of Type A behavior.     

An extension of the keyword method facilitates the acquisition of simple Spanish sentences

Subjects were taught Spanish-English paired-associates by using the keyword method. The item pairs ranged in length from one to four words. Subjects using the keyword method recalled many more constituents of n-a-v-n Spanish sentences than subjects spontaneously using rehearsal, but no more than subjects spontaneously using imagery. The results of the study suggest that the keyword method facilitates recall by inducing subjects to process item-specific information for individual words.     

Describing our “humanness”: Can genetic science alter what it means to be “human”?

Over the past several decades, geneticists have succeeded in identifying the genetic mutations associated with disease. New strategies for treatment, including gene transfer and gene therapy, are under development. Although genetic science has been welcomed for its potential to predict and treat disease, interventions may become ethically objectionable if they threaten to alter characteristics that are distinctively human. Before we can determine whether or not a genetic technique carries this risk, we must clarify what it means to be “human”. This paper inquires how “humanness” has been defined within various academic fields. The views of several legal theoreists, scientists, bioethicists, psychologists, philosophers and anthropologists whose works seem to best reflect how “humanness” is understood in their respective fields of study are considered. Our survey attempts to chart a path for a more detailed study on the meaning of “humanness” in the future. We assess four traits commonly identified in the literature as defining what it means to be human: cognition, biological or physiological composition, social interaction with other “human” beings, and spirituality. The nature of the relationship between these characteristics, in our view, is symbiotic: genetic intervention which alters one of them could have repercussions on one or more of the others. In conclusion, we offer guidance to those participating in genetic research and treatment regarding the parameters within which they may proceed without threatening the preservation of what is distinctively human.     

Item-specific effects in recognition failure: Reasons for rejection of the Tulving-Wiseman function

The present paper addresses the problems of whether recognition failure of recallable words is a function of both recognition and recall, and whether recognition failure is restricted to a small and specifiable subset of study items. A meta-analysis of the Nilsson—Gardiner database (Nilsson & Gardiner, 1993) showed that recognition given recall was positively correlated with recognition and negatively correlated with recall. Two new experiments are reported, the first one using 48 word pairs for which recognition failure was found in previous studies. An item analysis of the data demonstrated that recognition failure occurred primarily with noun—adjective pairs. The second experiment compared Norwegian—American and American—Norwegian name pairs. Wide deviation from the Tulving—Wiseman function (Tulving & Wiseman, 1975) was observed for the latter condition. In both conditions, recognition failure occurred with only the items for which the beginnings of names shared three or more letters. It is concluded that recognition failure occurs when there exists a relationship between the members of an A—B pair that is independent of their pairing in the study context. The Tulving—Wiseman function is the result of collapsing across items in the analysis of previous studies.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

The effect ofsome andall on reaction time for semantic decisions

Two experiments tested a model proposed by Meyer (1970) to account for the times required to verify semantic-memory statements quantified byall orsome. Each S was presented with bothall andsome statements in a mixed list, and the discriminability of false statements of the two quantifier types was controlled. In Experiment I positive subset statements ("horses are animals") were verified more quickly when quantified byall rather thansome; the reverse ordering occurred for negative subset statements ("horses are not animals"). Sentences with pseudowords in subject or predicate position took longer to reject than false real-word sentences. These findings contradict :Meyer's theoretical predictions and suggest that his earlier results were artifactual. Experiment II replicated the faster verification of positive subset statements quantified byall. This result was further shown to be predictable from the frequency with which Ss gave the predicate as a completion ofAll/Some S are _. The production frequency of predicates which form subset statements was lower when the quantifier wassome rather thanall. However, holding predicate production frequency constant, sentences with different quantifiers were verified equally quickly.