Two temporal parameters of food postponement

Rats were trained to press a lever under schedules of food postponement. In the absence of lever presses, food was delivered periodically (food-food interval). Responses initiated a second interval (response-food interval) that was reset by each additional response. Performance was first studied at different response-food intervals with the food-food interval fixed at 30 or 60 sec, or 10 min. Response-food intervals were examined in ascending order and then recovery was studied at shorter intervals. Finally, the food-food interval was manipulated with response-food interval fixed at 30 sec. At food-food intervals of 30 and 60 sec, responding first increased and then decreased as the response-food interval increased. At the 10-min food-food interval, responding decreased with increasing response-food interval. In general, very low rates of responding occurred when the response-food interval was 60 sec or more and when it equalled or exceeded the food-food interval. However, responding was maintained in one animal when the food-food interval was decreased from 120 to 15 sec with the response-food interval at 30 sec. Results, in terms of several dependent variables, are compared with data on shock avoidance. Effects of response-independent and response-produced food and shock are discussed.     

Preference for locus of punishment in a response sequence

Food-deprived pigeons pecked a key under a schedule in which grain was made available after the seventieth peck. In each sequence of 70 responses, either the first, middle, or final response was followed by electric shock. Before the first response of each sequence, each response on a second key changed the color of the food key and the schedule of shock that was correlated with the food key color. Each pigeon preferred a schedule of shock, in that each of the three shock schedules did not occur equally often. The preferred shock schedule and the strength of the preference varied among the pigeons. The overall rate of responding by a pigeon under a given shock schedule was directly related to the pigeon's relative preference for that schedule, except when shock after the first response in the sequence was the most preferred schedule.     

A method for the precise switching of speech

A simple procedure by which a speech signal may be switched on or off (or from one ear to the other) at a precise instant of time is described. The speech sample is first recorded on a magnetic tape loop. A reference pulse is then recorded preceding the speech signal. This reference pulse triggers an adjustable time delay which in tum operates an electronic switch at an appropriate time.     

Out of the frying pan into the goalbox

Using heat as a negative reinforcer was shown to be highly efficient in producing a discriminative response in Long-Evans rats. Heat failed to generate the emotional responses usually associated with shock as an aversive stimulus. In a separate study, using the heat-training procedure, age differences in the learning facility of Swiss/ICR (Ha) mice were detected.     

A comparison of leverpress and head-poke discriminated Sidman avoidance

A discriminated Sidman avoidance procedure used by Forgione (1970) was replicated using a head-poke response instead of a leverpress as the avoidance operant. The resultant data were described in terms of the five dependent measures reported by Forgione. Head-poke avoidance was found to be more efficient than its leverpress counterpart and compared very favorably with the lever-disabling (or shock-timer-on) procedure used by Forgione to break up inefficient leverpress behavior patterns.     

Functional equivalence between same-different classifications and judged similarity of Markov patterns

This experiment represented an initial at tempt at comparing same-different classifications and similarity judgments of Markov histoforms sampled from three different schema families. A measure of individual stimulus variability was more strongfy related to classification responses than to judged similarity. Dichotomous responses, derived from the similarity data by imposing threshold criteria, were found to be highly similor to real classification responses when the threshold values were estimated directly from the latter; little correspondence, however, was obtained using optimal classification criteria. The results support the notion that somewhat different features are used in making classification responses and similarity judgments, and indicate the need for developing more sensitive tasks involving controlled scanning of pattem information.     

Air-puff-elicited startle: Habituation over trials and measurement of a hypothetical emotional response

In the first of two experiments, it was demonstrated that an air puff elicited a reliable startle reflex in rats which showed no habituation over 50 trials. In the second study an attempt was made to measure an emotional response by recording startle reactions to the air puff during presentation of a presumed fear-eliciting CS. It was concluded that the air-puff-elicited startle reflex can be employed as an indirect measure of a hypothetical emotional response.