Delayed discrimination and delayed matching in pigeons

Three pigeons were each trained to perform a discrimination problem and a matching problem. Following acquisition, delays of 1 to 7 sec were interposed after stimulus presentation on both problems. Accuracy of responding on these two types of delay procedures was observed to be a function of length of delay interval. Performance was consistently poorer on the delayed matching problem than on the delayed discrimination problem.     

Assessment of retrieval strategy in incidental, intentional, and inclusion tests with word-fragment cues

The purpose of this study was to assess retrieval strategy in incidental, intentional, and inclusion tests with word-fragment cues following a levels-of-processing manipulation at study. The results of Exp. 1 showed small levels-of-processing effects in incidental tests, and most subjects reported involuntary rather than voluntary retrieval of study-list words. In an intentional test, although levels of processing had a much greater effect, quite a few subjects also reported involuntary rather than voluntary retrieval of study-list words, and these subjects showed a smaller effect of levels of processing than subjects reporting voluntary retrieval. These results suggest that subjects given instructions for both voluntary and involuntary retrieval of study-list words in an inclusion test might not in fact attempt voluntary retrieval at all, but simply adopt an involuntary retrieval strategy. The results of Exp. 2 provided evidence to support this suggestion. The general implication is that where test contamination refers to subjects' failure to use retrieval strategies in accordance with test instructions, inclusion tests can be contaminated, as well as incidental or intentional tests, and that it is always necessary to obtain converging evidence about the actual strategies subjects use.     

Encoding dimensions of subject-performed tasks

Summary In an experiment modelled upon the classical paradigm on release from proactive interference (PI), subjects were required to remember series of actions they had performed (e.g., roll the ball, fold the paper). The objects involved in these subject-performed tasks (SPTs) served as a basis for build-up and release of PI. The objects used in the first few trials of the experiment belonged to the same class (e.g., parts of the body), causing a build up of PI. A shift to a different class of objects (e.g., kitchen utensils) along four different dimensions (taxonomic category, weight, color, and size) was introduced to cause a release of PI. On the basis of PI-release experiments with words it was expected that shifts in taxonomic category would result in a greater release than shifts within any of the physical dimensions. However, the results revealed that the amount of PI release was, in general, larger than expected, and essentially the same for all four dimensions investigated. The results are discussed in terms of the nature of the memory representation of SPTs, and with regard to possible processing differences between SPTs and verbal information. In addition, methodological suggestions for furthering the understanding of the encoding and storage of action events are advanced.     

Motivation as a function of success frequency

Motivation and Emotion - It is well-established that intermediate challenge is optimally motivating. We tested whether this can be quantified into an inverted-U relationship between motivation and...     

Platelet MAO-B, personality, and psychopathology

The article investigates the relationships between platelet monoamine oxidase-B (MAO-B) activity, personality, and psychopathology (Diagnostic and Statistical Manual of Mental Disorders [4th ed.; American Psychiatric Association, 1994] diagnoses. These relationships were assessed in 178 incarcerated male juvenile delinquents. Even after controlling for smoking, the authors found that both Internalizing and Externalizing Psychopathology were negatively related to MAO-B activity. In the final reduced model, novelty seeking fully mediated the relationships between MAO-B and Externalizing Psychopathology but not between MAO-B and Internalizing Psychopathology. It was hypothesized that low platelet MAO-B activity does not directly predispose individuals to psychopathology but is related to specific personality traits, which in turn represent a vulnerability factor for psychopathology. Future studies should help clarify the nature of the relationships between personality, biological markers, and psychopathology.     

Stability, growth, and decline in adult life span development of declarative memory: cross-sectional and longitudinal data from a population-based study

Five-year changes in episodic and semantic memory were examined in a sample of 829 participants (35-80 years). A cohort-matched sample (N=967) was assessed to control for practice effects. For episodic memory, cross-sectional analyses indicated gradual age-related decrements, whereas the longitudinal data revealed no decrements before age 60, even when practice effects were adjusted for. Longitudinally, semantic memory showed minor increments until age 55, with smaller decrements in old age as compared with episodic memory. Cohort differences in educational attainment appear to account for the discrepancies between cross-sectional and longitudinal data. Collectively, the results show that age trajectories for episodic and semantic memory differ and underscore the need to control for cohort and retest effects in cross-sectional and longitudinal studies, respectively.     

Studying individual aging in an interindividual context: typical paths of age-related, dementia-related, and mortality-related cognitive development in old age

This study has 2 objectives: (a) to explore typical paths of cognitive development associated with aging, terminal decline, and dementia and (b) to promote and illustrate an individual-oriented approach to the study of cognitive aging based on longitudinal panel data from a population-based sample (N = 500; age range-sub(T1)= 60-80, where T refers to time) tested at 3 occasions 5 years apart. Results document interindividual differences in multivariate patterns of change. Although cognitive changes generally covary, the present study indicates that subgroups of individuals develop along different paths characterized by selective changes in subsets of cognitive functions. Typical progression of dementia followed a developmental cascade from low declarative memory, via low functioning across all observed cognitive measures, to dementia diagnosis, and finally, death.     

Enhanced occipital and anterior cingulate activation in men but not in women during exposure to angry and fearful male faces

Blood-oxygenation-level-dependent signal was measured with functional magnetic resonance imaging in 24 healthy young subjects (12 men and 12 women) during viewing of angry, fearful, and neutral male and female face pictures. Exposure to angry male as opposed to angry female faces activated the visual cortex and the anterior cingulate gyrus significantly more in men than in women. A similar sex-differential brain activation pattern was present during exposure to fearful but not neutral faces. Previous behavioral studies indicate enhanced physiological arousal in men but not in women during exposure to angry male as opposed to female faces, and brain imaging studies have shown that the occipital cortex and the anterior cingulate gyrus are influenced by activity in the autonomic nervous system as well as by visual attention. Hence, we suggest that the elevated occipital and anterior cingulate activation in men during confrontation with other angry and fearful males may reflect enhanced vigilance in a potentially dangerous situation.