Interacting Cache memories: evidence for flexible memory use by Western Scrub-Jays (Aphelocoma californica)

When Western Scrub-Jays (Aphelocoma californica) cached and recovered perishable crickets, N. S. Clayton, K. S. Yu, and A. Dickinson (2001) reported that the jays rapidly learned to search for fresh crickets after a 1-day retention interval (RI) between caching and recovery but to avoid searching for perished crickets after a 4-day RI. In the present experiments, the jays generalized their search preference for crickets to intermediate RIs and used novel information about the rate of decay of crickets presented during the RI to reverse these search preferences at recovery. The authors interpret this reversal as evidence that the birds can integrate information about the caching episode with new information presented during the RI.     

The genomic action potential

Neurons compute in part by integrating, on a time scale of milliseconds, many synaptic inputs and generating a digital output-the "action potential" of classic electrophysiology. Recent discoveries indicate that neurons also perform a second, much slower, integration operating on a time scale of minutes or even hours. The output of this slower integration involves a pulse of gene expression which may be likened to the electrophysiological action potential. Its function, however, is not directed toward immediate transmission of a synaptic signal but rather toward the experience-dependent modification of the underlying synaptic circuitry. Commonly termed the "immediate early gene" (IEG) response, this phenomenon is often assumed to be a necessary component of a linear, deterministic cascade of memory consolidation. Critical review of the large literature describing the phenomenon, however, leads to an alternative model of IEG function in the brain. In this alternative, IEG activation is not directed at the consolidation of memories of a specific inducing event; instead, it sets the overall gain or efficiency of memory formation and directs it to circuits engaged by behaviorally significant contexts. The net result is a sharpening of the selectivity of memory formation, a recruitment of temporally correlated associations, and an ultimate enhancement of long-term memory retrieval.     

Is parental divorce a critical stressor for young adolescents? Grade point average as a case in point.

Previous studies have shown parental divorce to be associated with poor functioning of children and adolescents. Almost all of the studies attempting to delineate these effects, and to shed light on the differences between boys and girls, have limited data collection to postdivorce. This practice has left a void in the picture of divorce--specifically in the area of predivorce effects. The purpose of the present study was to examine academic functioning of young adolescents with respect to both pre- and postdivorce effects. Fifty-eight young adolescents (29 from families which subsequently divorced and 29 from families which remained intact) were studied. Results indicated that boys from subsequently divorcing homes had significantly poorer academic functioning prior to their parents' divorce than did boys whose families remained intact and girls whose parents divorced. Differentially, girls from subsequently divorcing families showed a decline in academic functioning which began prior to divorce and continued beyond the time of divorce. Possible explanations for these gender differences are explored, and the importance of examining predivorce effects is addressed.     

On objectivity and subjectivity in statistical inference: A response to Mayo

In this paper we respond to the article An Objective Theory of Statistical Testing by D. G. Mayo (1983). We argue that the theory of testing developed by Mayo, NPT*, is neither novel nor objective. We also respond to the claims made by Mayo against Bayesian theory.     

Reactions to Social Categorization: Evaluating One Argument Against Affirmative Action1

One argument made against affirmative action is that it is undesirable or inappropriate to treat people on the basis of their group membership. The present study attempts to evaluate college students' opinions about this type of social categorization. Two variables were manipulated: type of social group (i.e., one based on race, gender, religion, sexual orientation, or college major), and the purpose of the categorization (to identify, to form a social group, to form a political group, or for affirmative action purposes). Results indicated that students were, in general, opposed to such social categorizations. The presence of interaction effects, however, suggests that opposition to affirmative action is not uniform across different target groups and is not based solely on objections to social categorization. Implications are discussed.     

Interference with real world knowledge

Two experiments are described in which subjects studied made-up, fantasy facts about well-known persons and then were asked to verify actual facts about these persons. Reaction time to the actual facts was longer the more fantasy propositions studied about a person. Reaction time was also longer when the verification test involved a mixture of actual and fantasy facts rather than just actual facts. A mathematical version of the ACT model (Anderson, 1976) was fit to the data. It provides a satisfactory fit, better than an alternate model. However, some of the parameter values estimated for the ACT model seemed unreasonable.     

A response duration schedule: effects of training, extinction, and deprivation

Rats were trained to hold down a lever for at least 40 consecutive seconds. When the lever had been held down for 40 sec, white noise came on. Releasing the bar in the presence of the noise turned off the noise and operated a feeder that delivered a pellet of food. At the end of training, frequency distributions of response durations peaked at 40 to 41 sec. If as in training, holding down the lever produced white noise at the end of 40 sec, and release of the lever terminated the noise and operated the feeder, but no food delivery occurred, duration distributions and several other measures were initially not very different from when food was delivered. However, if during extinction white noise was never produced by lever holding, and feeder operation did not occur upon lever release, most responses were shorter than 1 sec in duration, some were much longer than 41 sec, and duration distributions did not peak at 40 to 41 sec. When reinforcement was reinstated after extinction, performance quickly returned to pre-extinction measures. Further sessions at different levels of deprivation produced only temporary disruptions in performance.