CONTRACTUALISM AND ANIMALS

Philosophical Studies -     

Need probability affects retention: A direct demonstration

Recent memory theory has emphasized the concept ofneed probability—that is, the probability that a given piece of learned information will be tested at some point in the future. It has been proposed that, in real-world situations, need probability declines over time and that the memory-loss rate is calibrated to match the progressive reduction in need probability (J. R. Anderson & Schooler, 1991). The present experiments were designed to examine the influence of the slope of the need-probability curve on the slope of the retention curve. On each of several trials, subjects memorized a list of digits, then retained the digits in memory for 1, 2, 4, 8, or 16 sec. Some trials ended with a recall test; other trials ended with the message, “no test.” In Experiment 1, the likelihood of encountering a memory test (i.e., the need probability) was made to either increase or decrease as the retention interval increased; in Experiment 2, need probability either was flat (invariant across retention intervals) or decreased as the retention interval increased. The results indicated that the shape of the need-probability curve influenced the slope of the retention curve (Experiment 1) and that the effect became larger as the experimental session progressed (Experiment 2). The findings support the notion that memory adapts to need probabilities and that the rate of forgetting is influenced by the slope of the need-probability curve. In addition, all of the forgetting curves approximated a power function, suggesting that need probability influences the slope but not the form of forgetting.     

Neural Network Models and Mechanisms of Strategy Development

The focus of this paper is mechanisms that may be responsible for intellectual and developmental differences in the cognitive strategies of typical and atypical children, including those with mental retardation. The discussion of these mechanisms is based on behavioral experiments on external memory strategies and on a set of neural network models designed for these tasks. Following the review of the external memory research, the rationale for using neural network models, how they have been used in other research, and their specific application to intellectual and developmental differences in external memory, including the results of several simulations, are reviewed. This is followed by a discussion of the mechanisms of intellectual differences and developmental change included in the models and some challenges for this type of modeling. Neural network modeling is discussed as an asset to research on cognitive development.     

Deterrence, Opportunity, and Choice

Traditional studies of deterrence have focused on punishment with less regard for the rewards of both crime and noncrime. Influenced by work in economics and behavioral psychology, more recent studies have departed from tradition by incorporating rewards for crime. To this extent, they should be regarded as advances over the more traditional approaches. Notwithstanding these advances, variations in both the probability and magnitude of reward for noncrime have not been systematically included in these more recent theories of choice. In an attempt to determine whether opportunities for noncrime are either central or trivial to the criminal decision-making process, the present study fitted two alternative models to experimental data involving risk-taking: (a) the economic utility model employed by Piliavin, Gartner, Thornton, and Matsueda (1986) in their study of criminal choice; and (b) the satisfaction balance model developed by Gray and Tallman (1984). Results showed that while both models explained significant amounts of variation in the dependent variable, the Gray-Tallman model provided a substantially better fit of the data. Despite limitations inherent in experimental studies as, for example, limitations surrounding the issue of external validity, the findings strongly suggest that opportunities for noncrime are as important as rewards and costs for crime in the process by which criminal decisions are made.     

The Heritability of Characteristics Associated with Dispositional Empathy

ABSTRACT This investigation used data from Loehlin and Nichols's (1976) study of over 800 sets of twins to examine evidence for the heritability of three facets of empathy: empathic concern, personal distress, and perspective taking. Expert judges first identified sets of adjectives, included within Loehlin and Nichols's original data, which reflected each empathy construct; these items were then validated in an independent sample. Comparisons of the responses given to these items by identical and fraternal twins in the Loehlin and Nichols investigation revealed evidence of significant heritability for characteristics associated with the two affective facets of empathy—empathic concern and personal distress—but not for the nonaffective construct of perspective taking. This pattern is consistent with the view that temperamental emotionality may underlie the heritability of affective empathy.