Donald E. Mintz

Sequential effects in fixed-ratio postreinf orcement pause duration

Pigeons were run on fixed ratio schedules that alternated between pairs of long and pairs of short ratios. Length of ratio was differentially cued. The longest pause in response preceded the longer ratio. However, sequential effects were observed. These suggested a contrast effect rather than a direct relation between amount of responding preceding a pause and pause duration.

Force differentiation in human subjects

Force of response was differentiated in four human Ss using a quantitative visual feedback procedure. Variations in the force required produced systematic changes in rate of response and in the precision with which the response was made.

The effects of time-out duration during fixed-ratio reinforcement

Pigeon’s keypecking was reinforced on a multiple fixed-ratio (FR) schedule. All three components were maintained at a FR 50 response requirement with two components containing timeouts. A 2.5-sec time-out appeared regularly after the 30th response in one of these components, while a 10-sec time-out appeared after the 30th response in the second time-out component. Pauses following reinforcement were shortest in the non-time-out component, while longest duration pausing accompanied the 10-sec time-out component. The 2.5-sec time-out generated intermediate duration pauses. In time-out components, response rate was low preceding the time-out, and high immediately following it. The total time from response initiation to subsequent reinforcement was highly predictive of pause duration.

The effects of time-out locus during fixed-ratio reinforcement

Pigeon’s keypecking was reinforced on a multiple fixed-ratio schedule. All three components were fixed ratio 60; a 10-sec time-out regularly appeared after the tenth response in one component and after the fiftieth response in another. Pause duration was shortest with no time-out, longest with the time-out late in the ratio. In time-out components, response rate was low preceding the timeout, high immediately following it. The total time from rsponse initiation to subsequent reinforcement was highly predictive of pause duration. Immediate repetition of a component generally produces shorter pausing than when it was preceded by a different component.

Pause and rate effects in multiple-reinforcement fixed ratio schedules

Fixed ratio schedules were employed in which the number of unreinforced responsed per reinforced sequence was kept constant but the number of successive reinforced responses was systematically varied from one to four. Both higher run rates and shorter pauses in responding following reinforcement were related to greater numbers of reinforcements for the pigeons used in this study. With more than one reinforcement the post-reinforcement pause was frequently preceded by a short burst of responses.

Pausing in multiple fixed- ratio schedules

Pigeons were maintained on multiple fixed-ratio schedules with food reinforcement for a keypeck response. A regular pattern of short-short-long-long-etc. was employed for the fixed-ratio sequence within a session. Pausing following reinforcement was shown to be determined by the length of the forthcoming fixed ratio, the relation of this fixed-ratio length to the schedule paired with it, and the place of the fixed ratio in the patterned sequence. The sequential effect indicated shorter pauses for a given fixed ratio when its completion would be followed by the shorter fixed ratio, and longer pausing at the point of transition from a shorter to a longer fixed ratio.

Drug effects in fixed ratio matching to sample

Pigeons’ fixed ratio matching-to-sample performance was examined under varied Librium and d-amphetamine doses. Both the response rate and the distribution of errors within the ratio were affected. Latencies of matching attempts for errors and correct matches differed, and this relationship was influenced by drug level and position of the trial within the ratio.

Human force differentiation: Indifference to pressure

A force of 150 g (1.47 N) was differentiated in two human Ss. The diameter of the circular lever surface they pressed was varied to achieve pressure differences on the responding finger. Neither the central tendency nor the variability of the performance were influenced by the variations in pressure.