Looking time: Experimenter and instruction effects

A 2 by 3 factorial design was used to investigate the effects of the instructions and the presence of E on looking time. Two hundred thirty-nine college students viewed 30 colored stimuli of landscapes, single objects, and arrays of objects under three different sets of instructions, with E either present or absent while S viewed the stimuli. The results demonstrated that E’s presence depressed the time spent looking at the stimuli Evidence was also found suggesting that ambiguity in the typical instructions given Ss in looking-time experiments may result in artifactually long looking times. It was concluded that a more appropriate situation to investigate looking time would (1) utilize sham GSR instructions to reduce S’s uncertainty concerning the experiment’s purpose, and (2) arrange for E’s absence while S is viewing the stimuli     

Sense modality switching and serial leaming

This investigation examined the effect of sense modality switching ofinformation at various positions of a serial learning task. Different numbers of flashes of light and different numbers of “blips” ofa pure tone were used as signalsin a four-position serial learning task. The design of the study involved a switch in sense modality at each one of the four possible positions in the series. Thus, it was possible to determine if the transmission of information through one sense modality makes it progressively more difficult or more time consuming to switch to another source of information transmitted through another modality. The results generally supported the contention that, as information is received through a particular modality, there is a build-up of the disruption involved in switching sense modality.     

Responding under fixed-ratio and multiple fixed-interval fixed-ratio schedules of electric shock presentation

Squirrel monkeys, initially trained under a schedule of electric shock postponement and then under fixed-interval schedules of electric shock presentation, were studied under multiple fixed-interval fixed-ratio and under fixed-ratio schedules of shock presentation. Under the fixed-interval (10-min) component of the multiple schedule, a pause was followed by a gradual increase in responding to a rate maintained until shock presentation; under the fixed-ratio (3-, 10-, or 30-response) component of the multiple schedule, a brief pause was typically followed by a relatively high and uniform rate of responding until shock was presented. When the 60-sec timeout periods, which usually followed shock presentation, were eliminated from the multiple schedule for one monkey, responding was only transiently affected. In the one monkey studied, responding was maintained under a fixed-ratio schedule alone (with timeout periods), but rates of responding were lower than under the fixed-ratio component of the multiple schedule. Characteristic patterns of responding, similar to those engendered under schedules of food presentation or shock termination, can be maintained under fixed-ratio schedules of shock presentation; further, patterns of responding can be controlled by discriminative stimuli in multiple schedules.     

Two-key concurrent responding: response-reinforcement dependencies and blackouts

Two-key concurrent responding was maintained for three pigeons by a single variable-interval 1-minute schedule of reinforcement in conjunction with a random number generator that assigned feeder operations between keys with equal probability. The duration of blackouts was varied between keys when each response initiated a blackout, and grain arranged by the variable-interval schedule was automatically presented after a blackout (Exp. I). In Exp. II every key peck, except for those that produced grain, initiated a blackout, and grain was dependent upon a response following a blackout. For each pigeon in Exp. I and for one pigeon in Exp. II, the relative frequency of responding on a key approximated, i.e., matched, the relative reciprocal of the duration of the blackout interval on that key. In a third experiment, blackouts scheduled on a variable-interval were of equal duration on the two keys. For one key, grain automatically followed each blackout; for the other key, grain was dependent upon a response and never followed a blackout. The relative frequency of responding on the former key, i.e., the delay key, better approximated the negative exponential function obtained by Chung (1965) than the matching function predicted by Chung and Herrnstein (1967).     

Rate-dependent effects of drugs: modification by discriminative stimuli of the effects of amobarbital on schedule-controlled behavior

Food-deprived pigeons responded under a 10-min fixed-interval schedule of food presentation. During even-numbered minutes of the schedule, the discriminative stimuli were the same as those present when food was delivered. During odd-numbered minutes there was either a change in keylight color or a change in overhead illumination, either for the entire duration of the odd-numbered minutes, or for 3-sec after each response. Responding during even-numbered minutes showed the usual pattern of positive acceleration; responding during odd-numbered minutes was similarly graded, but rates were much lower. The response-rate-increasing effects of amobarbital were inversely related to control rates of responding for both even- and odd-numbered minutes. However, when the stimulus change during odd-numbered minutes was either keylight color or a change from a darkened to a brightly illuminated chamber, increases in responding were considerably less than predicted on the basis of the effects on responding during even-numbered minutes. When the stimulus change was from a darkened to a dimly illuminated chamber, control rates of responding changed little, but increases in responding during odd-numbered minutes after amobarbital were considerably greater, and of the approximate order expected on the basis of control rate.