Sexual experience and preference for males or females in the female rat

The influence of sexual experience on preference behavior was investigated in adult female rats. In the first experiment, preference behavior for sexually active males versus estrous females was investigated in female rats who were experienced with mounting behavior. Preference of these mount experienced females was compared to preference of females who were naive in this respect. Mount experience with estrous females induced a female-directed preference in ovariectomized female rats, irrespective of whether the females were treated with OIL or with testosterone-propionate (500 micrograms TP, injected once 48 h prior to testing). Sexually naive, OIL-treated females did not show a preference for males or females, but TP induced a preference for a male. Individual differences in mount frequency were not correlated with preference behavior. In the second experiment, the influence of experience with feminine sexual responses on preference behavior was investigated. OIL-treated and TP-treated females oriented equally toward males and females when they had been given the opportunity to copulate with males prior to the preference tests. The results strongly suggest that prior sexual experience is an important determinant of preference behavior. The female's behavior during sexual interactions was, however, not predictive of later preference.     

Anisomycin impairs long-term working memory in a delayed alternation task

A long-term temporal component of working memory of rats trained on the radial maze has been shown to be susceptible to disruption by the protein synthesis inhibitor, anisomycin. It is not clear whether protein synthesis played a role in working memory because accurate performance on the radial maze required the storage of a large amount of information, or because the information was to be held in store for relatively long periods of time. This experiment tested these hypotheses by assessing the effect of anisomycin on choice accuracy in a comparatively simple spatial delayed alternation task. Results indicate that under the present training conditions, protein involvement in working memory is related more to the length of the retention interval than to the amount of information retained.     

The relationship of affiliative arousal to dopamine release

Higher levels of affiliation motivation after exposure to affiliative films are significantly related to higher dopamine concentrations in saliva in one study of 61 college students of both sexes, and in plasma in another study of 47 adults of both sexes. Individuals high in dispositionaln Affiliation, if they also reported high life stress, showed high gains in dopamine concentration in plasma after exposure to an affiliative film significantly more often than other individuals. Since aroused affiliation motivation was not associated with higher concentrations of norepinephrine, epinephrine, or cortisol in either study, it appears likely that dopamine is especially associated with arousal of affiliation motivation, just as norepinephrine has been found to be associated with arousal of power motivation. Thus, different motives may be subserved by different hormones, making it unlikely that all motives lead to the same state of physiological arousal.This research was carried out when all the authors were connected with the Department of Psychology and Social Relations at Harvard University. We acknowledge with thanks the support of the John D. and Catherine T. MacArthur Foundation through a grant to the senior author.     

Modification of Type A behavior through aerobic exercise

This psychophysiological evaluation of an aerobic exercise program examined specifically whether aerobic training modified Pattern A for those individuals at behavioral risk for developing coronary heart disease, i.e., young Type A individuals. At pretest and posttest of this secondary prevention study, Type A and Type B subjects were assessed in three conditions: aerobic exercise program, nonaerobic activity (Aikido, a martial art) control, and notreatment control. After 10 weeks, Type A but not Type B subjects exhibited lower Pattern A behavior in the aerobic program than in control conditions. Average workout pulse rates and differentially reliable increases in aerobic capacity indicated that aerobic training was indeed aerobic, whereas aikido activity was not. Even though selected nonaerobic factors, such as locus of control and group participation, did not mediate the Pattern A decrease for Type A's when comparing aikido and aerobic conditions, changes in aerobic capacity may have been the mediator. Generalizability of the results and implications for theoretical development and clinical intervention are discussed.     

Structure and process in semantic memory: new evidence based on speed-accuracy decomposition

Reaction-time and accuracy data obtained from studies of sentence verification have not been rich enough to answer certain important theoretical questions about structures and processes in human semantic memory. However, a new technique called speed-accuracy decomposition (Meyer, Irwin, Osman, & Kounios, 1986) may help solve this problem. The technique allows intermediate products of sentence verification to be analyzed more precisely. Three experiments with speed-accuracy decomposition indicate that verification processes produce useful partial information before they are completed. Such information appears to accumulate continuously at a rate whose magnitude depends on the degree of relatedness between semantic categories. This outcome is consistent with continuous computational (e.g., semantic-feature comparison) models of semantic memory. An analysis of reaction-time minima suggests that a discrete all-or-none search process may also contribute at least occasionally to sentence verification. Further details regarding the nature of these processes and the memory structures on which they operate can be inferred from additional results obtained through speed-accuracy decomposition.     

Time horizons in rats foraging for food in temporally separated patches

An important tenet of optimal foraging theory is that foragers compare prey densities in alternative patches to determine an optimal distribution of foraging behavior over time. A critical question is over what time period (time horizon) this integration of information and behavior occurs. Recent research has indicated that rats do not compare food density in a depleting patch with that in a rich patch delayed by an hour or more (Timberlake, 1984). In the present research we attempted to specify over what time period a future rich patch would affect current foraging. The effect of future food was measured by early entry into the rich patch (anticipation) and by a decrease in food obtained in the depleting patch (suppression). The rats showed anticipation of a rich patch up to an hour distant, but suppressed current feeding only if the rich patch was 16 min distant or less. The suppression effect appeared mediated by competition for expression between anticipatory entries into the rich patch and continued foraging in the depleting patch. These results suggest that optimal foraging is based on a variety of specific mechanisms rather than a general optimizing algorithm with a single time horizon.     

Social structure features in three inbred strains of mice, C57Bl/6J, Balb/cj, and NIH: a comparative study

Some features of social living were investigated in three inbred strains of mice: C57Bl/6j, Balb/cj, and NIH. Five social behaviors--Aggression, Submission, Allogrooming, Social Rest and Rest Alone, as well as Wheel Running Activity--were recorded 2 h daily for a week, in 26 groups of seven male mice living in an enriched environment. Dominants and subordinates among strains shared some behavioral characteristics, but strain contributions upon social structure were also detected. Similarities among strains included the appearance of a single dominant mouse per group rated as the most aggressive, besides from being the animal presented with most Submissions. Allogrooming was more frequent among subordinates than among dominants and subordinates. Differences among strains were that agonistic behavior among subordinates was higher in the Balb/cj and NIH groups than in the C57Bl/6j mice. NIH mice were recorded in Rest Alone more often than mice from the other strains. C57Bl/6j dominants showed higher rates of Wheel Running Activity than subordinates.     

Pavlovian analysis of interactions between hunger and thirst

In four experiments we examined the effect of an irrelevant drive on classical conditioning with food and water. In the first experiment the irrelevant drive weakened the conditioned response in extinction. In Experiments 2 and 3, this suppressive effect was found also in acquisition. Furthermore, the presence of an irrelevant drive during nonreinforced presentations of the conditioned stimulus was found to protect the conditioned response from extinction. Experiment 4 showed that the depressive effect of the irrelevant drive is manifested only when the relevant drive is present. Taken together, these results suggest that an irrelevant drive can influence conditioned responding by modulating the representation of the unconditioned stimulus.     

Effects of foveal priming and extrafoveal preview on object identification

The results of three different experiments suggested that the relation between an object in the fovea on fixation n and an object subsequently brought into the fovea on fixation n + 1 affects the time to identify the second object. In Experiment 1 we extended previous work by demonstrating that a previously seen related priming object speeded the time to name a target object even when a saccade intervened between the two objects. In Experiment 2 we replicated this result and further showed that the benefit on naming time was due to facilitation from the related object rather than inhibition from the unrelated object. In addition, naming of the target object was much slower in both experiments when there was not a peripheral preview of the target object on fixation n. However, because the effect of the foveal priming object was greater when the target was not present than when it was present, priming did not appear to make extraction of the extrafoveal information more efficient. In Experiment 3, fixation times were recorded while subjects looked at four objects in order to identify them. Fixation time on an object was shorter when a related object was fixated immediately before it, even though the four objects did not form a scene. The size of the facilitation was roughly comparable to that in several analogous experiments where scenes were used. The results suggest that the effects of a predictive scene context on object identification may be explainable in terms of an object-to-object or "intralevel" priming mechanism.     

Rigidity in cinema seen from the front row, side aisle

Pictures and cinema seen at a slant present the optics of virtual objects that are distorted and inconsistent with their real counterparts. In particular, it should not be possible for moving objects on slanted film and television screens to be seen as rigid, at least according to rules of linear perspective. Previous approaches to this problem have suggested that some process (perhaps cognitive) rectifies the optics of objects in slanted pictures to derive true shape and preserve shape constancy. The means for this rectification is usually thought to be based on recovery of true screen slant. In three experiments I show that this account is unnecessary and insufficient to explain the perception of rotating, rectangular objects in slanted cinema. I present data in favor of an alternate view, one in which the information is sufficient for perceivers to determine rigidity in an object on slanted screens, at least for parallel projections. In the human visual system, local measurements of objects are apparently made according to projective geometry; in those measurements, small amounts of certain distortions in projection are tolerated. Stimuli that appear nonrigid are ones that violate certain local principles, known as Perkins's laws, of projections of rectangular solids.