Discrimination and generalization by rats of temporal stimuli lasting for minutes

In three experiments, rats learned to respond differentially to reinforced and nonreinforced trials when the length of the intertrial interval (ITI) predicted the trial outcome (reinforcement or nonreinforcement). Rats in control groups, for whom the length of the ITI did not predict the outcome, did not show differential performance on nonreinforced and reinforced trials. Generalization gradients obtained following discrimination training were comparable to those obtained following discrimination training with other types of discriminative stimuli. That is, groups which had shown differential performance in discrimination training yielded generalization gradients with fastest speeds at the previously reinforced ITIs, slowest speeds at the previously nonreinforced ITIs, and intermediate speeds at ITIs of intermediate length. Control groups yielded flat gradients across all ITIs tested. These effects were shown for relative time discrimination (short time = reinforcement, long time = nonreinforcement, or the reverse) and also for an absolute time discrimination (long and short time = reinforcement, middle time = nonreinforcement or the reverse). This method was effective for time duration measured in minutes rather than seconds, as is more commonly the case.     

A low-stress restraint procedure for EEG acquisition in awake rats

A restraint procedure was developed to reduce movement-related artifacts during the acquisition of EEG data from unanesthetized, unparalyzed rats. It combines the low-stress properties of a cloth restraint bag with the improved immobility of a rigid restraint device. The spontaneous behavior of the rat facilitates both the induction of and the subsequent release from restraint.     

The PSYCHLAB programming system: A tool for developing experimental control programs

The PSYCHLAB system is designed to facilitate the task of writing experimental control programs. The system consists of two major components: (1) a collection of procedures and functions to facilitate presenting stimuli, collecting responses, and measuring response times and (2) a high-level language (LAB-TALK) designed to organize and sequence events in experiments. The PSYCHLAB system is formally an interpreter that will interpret programs written in LAB-TALK. The interpreter is customized to perform the detailed functions of each trial in an experiment. The occurrence of these trials is controlled by the LAB-TALK program. Thus, once a particular experimental paradigm has been represented in a customized version of the interpreter, many different experiments in that paradigm can be programmed by variations in the LAB-TALK program.     

Adolescent Smoking Behavior and the Recognition of Cigarette Advertisements1

In a study designed to assess the relationship between smoking status and correct identification of cigarette brands, junior high school students from two schools viewed cigarette and automobile advertisements with brand and model identification deleted. Results showed that adolescents with higher ad recognition scores were more likely to smoke cigarettes. In addition, a relationship was found between age and correct identification of cigarette advertisements, with older students identifying more ads correctly than younger students. No significant effects emerged for identification of automobile advertisements except for sex, with boys identifying more advertisements than girls. Additional findings indicated that even “experimental” smokers, who smoked as little as once per year, recognized significantly more cigarette advertisements than nonsmokers. These and other results are discussed in terms of their implications for prevention and policy issues. It is argued that society's allowance of printed cigarette advertising overlooks adolescents' heightened vulnerability to the kinds of appeals used in cigarette advertisements. Present policy also overlooks adolescents' relative unresponsiveness to the health risk information required in cigarette advertisements.     

Menstrual cycle affects kinesthetic aftereffect, an index of personality and perceptual style

Research suggests that kinesthetic aftereffect (KAE) scores reflect status on a postulated stimulus intensity modulation (SIM) mechanism that damps down subjective stimulus intensity for some (reducing) and increases it for others (augmenting). Such a mechanism would help account for empirically observed individual differences in such behaviors as pain tolerance, sensory deprivation reactivity, and stimulation seeking. It was hypothesized and confirmed in three adult female samples that KAE varies curvilinearly over the menstrual cycle: Greater KAE reduction occurs at the cycle's beginning and end. Neither tiredness, oral contraception, medication, attention, nor social expectations can explain this finding. Of the behaviors studied in the KAE literature, only five are also encompassed by the menstrual cycle literature. Four of these (antisocial behavior, acute schizophrenic episodes, accidents, and activity level) show similar curvilinearity over the cycle. We hypothesize that cyclical variation in the SIM mechanism mediates the curvilinear pattern observed for both these four behaviors and KAE.     

A cusp catastrophe: Hysteresis, bimodality, and inaccessibility in rabbit eyelid conditioning

Three properties of the cusp catastrophe: bimodality, inaccessibility, and hysteresis were evaluated in rabbit eyelid conditioning. Bimodality was evidenced by the fact that responding tended to occur at either very low or very high levels, and inaccessibility by the fact that intermediate levels of responding were rarely encountered. Hysteresis was demonstrated when: (a) levels of responding attained under a continuous schedule of reinforcement were largely maintained by a schedule which was too lean to promote conditioning by itself; and (b) levels of responding attained with a high intensity unconditional stimulus were largely maintained by a lower intensity unconditional stimulus which was too weak to promote conditioning in its own right. These results are consistent with the model of conditioning suggested by P. W. Frey and R. J. Sears (Psychological Review, 1978, 85, 321–340) which postulates response-mapping rules based on the cusp catastrophe.