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.     

Hippocampal synaptic plasticity during instrumental learning

present research examined the role of hippocampal NMDA-dependent synaptic potentiation on appetitive instrumental conditioning under a continuous reinforcement schedule. In the first experiment, low (.025 mg.kg) or moderate (.05 mg/kg) dosages of the NMDA receptor antagonist, MK801, failed to increase the number of training days required to reach acquisition criterion; number of training days required to reach criterion for extinction were also unaffected. In the second experiment, a higher dosage (.10 mg/kg) of MK801 or induction of long-term potentiation failed to alter the number of responses occurring during acquisition. These data suggest that hippocampal synaptic potentiation does not play a prominent role in instrumental learning with simple contingency conditions. It is suggested that hippocampal LTP reflects a perceptual process that contributes differentially to spatial cognition, classical and instrumental conditioning.     

Hippocampal synaptic plasticity during instrumental learning

present research examined the role of hippocampal NMDA-dependent synaptic potentiation on appetitive instrumental conditioning under a continuous reinforcement schedule. In the first experiment, low (.025 mg.kg) or moderate (.05 mg/kg) dosages of the NMDA receptor antagonist, MK801, failed to increase the number of training days required to reach acquisition criterion; number of training days required to reach criterion for extinction were also unaffected. In the second experiment, a higher dosage (.10 mg/kg) of MK801 or induction of long-term potentiation failed to alter the number of responses occurring during acquisition. These data suggest that hippocampal synaptic potentiation does not play a prominent role in instrumental learning with simple contingency conditions. It is suggested that hippocampal LTP reflects a perceptual process that contributes differentially to spatial cognition, classical and instrumental conditioning.     

Construct validity and test-retest reliability of a date rape decision-latency measure

In two studies, the construct (convergent and discriminant) validity and test-retest reliability of a date rape decision-latency measure was examined. In Study 1, 174 college men completed measures related to sexual aggression and listened to an audiotaped simulation of a date rape, during which cues of nonconsent and force gradually escalated over time. Participants were instructed to respond, by pressing a button which recorded the latency of their decisions in seconds, if and when they believed the man depicted in the scenario should stop his sexual advances. Results demonstrated positive associations between prolonged decision latencies and sexually aggressive behavior, calloused sexual beliefs, acceptance of interpersonal violence, and sexual promiscuity. In Study 2, initial results were cross-validated in a sample of 102 college men, and discriminant validity was established as decision latencies were unassociated with measures of social desirability, alcohol consumption and drug use. Test-retest reliability assessed over a 2-week interval was .87.The authors wish to thank Alan Gross and Brian Marx for providing the audiotaped stimulus materials, Richard Marsh for writing the decision-latency computer program, Jason Hicks for assisting with programming, and the undergraduate research assistants for serving as experimenters.     

New Roles for Rhetoric: From Academic Critique to Civic Affirmation

The classical conception of rhetoric as the method of reasoned political judgment survived into the Renaissance but was reduced to academic critiques of style and "empty" public rhetoric with the rise of modern science and its representationalist theories of language. Recently, however, rhetoric, textuality, and the "linguistic turn" generally, have become central metaphors in the human sciences. This renewed rhetorical perspective not only fosters a critique of positive philosophy and of scientism in public discourse, it also offers affirmative methods by which persons can construct their civic lives.