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     

The elimination of interfering response patterns in lever-press avoidance situations

Lever holding into shock and short-latency responses to shock onset are two response patterns that interfere with avoidance acquisition in free-operant and discriminated avoidance situations. In an attempt to eliminate these patterns, an additional timer disabled the lever for a period slightly longer than shock duration. A free-operant avoidance schedule with a warning stimulus, but without the additional timer, constituted the control condition. The lever-disabling timer was turned on by different events in two experimental conditions: (a) release of the lever at the onset of shock, (b) shock onset. Interfering responses diminished most rapidly, and efficient avoidance behavior appeared earliest, when the lever-disabling timer was turned on by shock onset.     

Effects of a conditioned reinforcer upon accuracy of match-to-sample behavior in pigeons

Three pigeons were trained to perform a two-key sequential match-to-sample task. During baseline conditions, food reinforcement was contingent upon the first match response to occur following 8-min periods, and orange illumination of both keys preceded the delivery of food by 0.5 sec. The baseline schedule of food reinforcement was in effect throughout the study. In some conditions, a 0.5-sec flash of orange keylight alone was presented contingent upon mismatch responses that followed variable time periods averaging 1 min. Rate of mismatch responses increased and accuracy of matching performances decreased as compared with baseline conditions. The ability of the 0.5-sec orange flash to reinforce mismatch responses was markedly reduced when it no longer immediately preceded the delivery of food.