Knowledge that Transforms

Second-order classical (Pavlovian) aversive conditioning was used to determine whether endogenous opiates play a role in the acquisition of associative learning. Second-order conditioning avoids confounding drug effects on associative learning with altered responsiveness to unconditioned stimuli (e.g., hyperalgesia). Administration of the prototypical opiate antagonist naloxone (2.0 mg/kg) prior to the second-order training session specifically facilitated associative learning as indicated by greater lick suppression over 3 days of testing. This result suggests that endogenous opiates retard the acquisition of associative learning, which complements previous studies demonstrating an opioid attenuation of memory consolidation.

There is greater unity in psychology than our internal squabbles might suggest because Mother Nature uses the same tricks in many contexts. There are fundamental principles that apply widely in psychology and have parallels in biology and physics. Behavior is a function of potentials that become manifest when the strenght of instigation to action exceeds a threshold. Thresholds result from exciting and inhibiting tendencies that are instigated along with a response of interest. Adaptive behavior is a blend of just two possibilities available to organisms, changing themselves to accommodate an unyielding environment or changing the world to meet their needs.

Hormones secreted from the pituitary-adrenal system during stress affect learning and memory processes. The phenomenon of long-term potentiation (LTP) is a robust example of neuronal plasticity and has become widely regarded as a possible physiological substrate for learning and memory in the mammalian brain. The current study supports our previous finding that stress impairs LTP in the in vitro hippocampal slice. In addition, manipulation of the pituitary-adrenal axis by dexamethasone (DEX), a synthetic glucocorticoid that blocks the pituitary-adrenal response to stress, appears to influence the temporal patterns of the development of the neuronal plastic changes which occur immediately after tetanus (post-tetanic potentiation period, or PTP). Since the stress-induced impairment of LTP occurs, regardless of DEX treatment, we suggest the action of DEX is to modulate the temporal pattern of the PTP/LTP interaction in response to stress.

J.P. Rushton has presented a series of articles proposing that different racial groups, having evolved under different environmental conditions, have been differentially selected, resulting in genetic differences in their reproductive behavior, intelligence, and “social rule-following.” Rushton's model is discussed with respect to two controversial points: criticisms of the nature of the data and analyses, and alternative explanations of the data. I concur with Rushton in the belief that different human groups utilize different strategies, but find the differential use of species-wide, environmentally contingent tactics a more parsimonious explanation than genetic differences.

Beginning with an analysis of a famous quotation from James’ Principles, this essay details some of the highlights of James’ treatment of sensation and perception. The primary source is a chapter on discrimination and comparison, in which emphasis is placed on the way people react to difference and sameness, reactions that may be fundamental to the psychophysical methods developed by Fechner and to later techniques, such as stimulus scaling and signal detection procedures, as well as to recent methods (preferential looking and habituation-dishabituation) for investigating perception in human infants. One can see considerable continuity between many of the issues raised in the Principles and those that have been addressed by perceptionists over the ensuing century, but James seems not to have had the direct impact in this domain that he has had, for example, on current conceptions of emotional processes. His associationist and functionalist positions may find contemporary expression in the seemingly disparate approaches known as connectionism and ecological psychology.

This article discusses the application of psychological theory and research on attributions, interpersonal relationships, and human territorial functioning to issues and assumptions in the law of searches and seizures, in particular, searches not based on a warrant, but on consent by the suspect or an appropriate third party, such as the suspect's spouse.