Mitri E. Shanab

The effects of self-perception and perceptual contrast upon compliance with socially undesirable requests

The relative effects of self-perception and perceptual contrast upon rate of compliance with a counter-normative request were studied in a 5 by 2 by 2 design that combined five sizes of the initial request, two levels of authority, and sex. Increased compliance was obtained only when the initial requests were either moderately small or excessively large, but not when they were either very small or moderately large.

A cross-cultural study of obedience

Using Milgram’s paradigm, 48 Jordanian college students were tested for obedience. It was found that the experimental subjects gave significantly more shocks than the control subjects. Unlike the experimental subjects, the control subjects were free to either give or not give shock. There was no difference in obedience rate between male and female subjects. In terms of overobedience, 62.5% of the experimental and 12.5 of the control subjects continued to deliver shock to the end of the shock scale.

The effects of delay upon compliance with socially undesirable requests in the door-in-the-face paradigm

The efficacy of the foot-in-the-door technique for inducing compliance with socially undesirable requests was investigated using a delay procedure. After refusing the first large request, experimental subjects were presented with a moderate request, which involved a concession on the part of the requester, a relative gain to the subject, or both. The control subjects received the second request only. No significant differences were found between the experimental and control groups. The results were discussed in terms of both contrast and self-perception explanations.

Positive contrast obtained in reacquisition following interpolation of nonreinforced or partially reinforced trials

Abstract Two experiments investigated the effects of shifting from either nonreinforcement or partial reinforcement (PRF) to continuous reinforcement conditions (CRF). In the first experiment, three groups of rats were given food reinforcement under CRF conditions in a runway followed by regular extinction trials (RE), extinction trials where S s were delayed for 30 sec before entering the empty goal box (DE), or CRF trials where S s were delayed for 30 sec before entering the baited goal box (DF). Then all S s were run on the delayed reinforcement condition (DF). In the final delayed reinforcement condition, group DE ran significantly faster than group DF, reflecting positive contrast. In the second experiment, four groups of rats were trained in a runway to receive either 4% or 18% sucrose reinforcers under either PRF or CRF conditions. Then all S s were transferred to a Skinner box and bar presses were continuously reinforced, with each S continuing to receive the same sucrose concentration as before. The former PRF S s, regardless of the reinforcer, bar pressed at a significantly higher rate in the Skinner box than the former CRF S s. The evidence seemed to favor the view that the effectiveness of a reinforcer is not an absolute, unchanging quantity but rather depends on the historical context in which the reinforcer occurs.

Positive contrast obtained in rats following a shift in schedule, delay, and magnitude of reward

Sixty-four rats were used in a 2 by 2 by 2 factorial design (Phase 1) which combined two levels of delay schedule (partial vs. continuous), two levels of magnitude of reward (1 vs. 22 pellets), and two levels of delay of reward (10 vs. 30 sec). On each trial in Phase 2, each subject received 22 pellets after a 10-sec delay interval. A significant positive contrast effect was obtained when all three variables of magnitude, delay, and schedule were upshifted. Similarly, positive contrast was obtained based on a shift in delay and schedule, magnitude and schedule, and magnitude and delay. Moreover, positive contrast was obtained based on either an upward shift in schedule or magnitude. A simple decrease in delay of reward did not produce positive contrast. The results were viewed as favoring relative rather than absolute theories of reinforcement. However, a modified sequential (capaldian) interpretation of positive contrast was also offered.

Negative contrast effect obtained with downshifts in magnitude but not concentration of solid sucrose reward

In Experiment I, hungry rats first received 10 pellets of either 4% or 16% sucrose, and later received one pellet of the same concentration as before. Control subjects received one pellet of either 16% or 4% throughout. A significant negative contrast effect was obtained with both concentrations. In Experiment II, three groups received four pellets of either 4%, 8%, or 16% sucrose concentration before receiving the same number of pellets of 8% concentration. Neither a positive nor a negative contrast effect was found. The results were discussed in terms of both the frustration and generalization-decrement hypotheses.

Positive and negative contrast effects obtained following shifts in delayed water reward

In a two-shift experiment, four independent groups of thirsty rats were delayed 20 sec before receiving the following treatments: LLL, LSL, SSS, SLS, with each letter denoting the magnitude of water reward received in each of the three phases of the experiment. Both a significant positive contrast effect (PCE) and a negative contrast effect (NCE) were obtained following the first shift. Weaker contrast effects were found in the second shift. The present results support and extend the generality of previous findings of studies using shifts in magnitude of food reward with superimposed delay as a control for ceiling effects.

The effects of shifts in delay of liquid sucrose reward in thirsty rats

In a two-shift experiment, four independent groups of thirsty rats received the following treatments: NNN, DDD, NDN, and DND, with each letter denoting the duration of the delay (0 or 30 sec) before receipt of the sucrose reward in each of the three phases of the experiment. While no reliable positive contrast effect was obtained in either shift phase, a significant negative contrast effect was obtained in both shift phases. The paucity of empirical data in this area hinders adequate explanatory attempts.

Contrast effects as a function of delay and shifts in magnitude of water reward in thirsty rats

In a two-shift experiment, eight independent groups of thirsty rats received the following treatments after either 0- or 15-sec delay: LLL, LSL, SSS, SLS, with each letter denoting the magnitude of water reward received in Phases 1-3 of the experiment. In the delayed condition, significant positive (PCE) and negative (NCE) contrast effects were obtained following the first shift, but only a weak PCE in the second shift. In the immediate reward condition, neither a PCE nor a NCE was obtained in either shift. The present findings are discussed in terms of several theories of contrast. The need for considerably more empirical investigations of shifts in the parameters of water reward was indicated.

The effects of repeated shifts in magnitude of food reward upon the barpress rate in the rat

In a four-shift experiment, four independent groups of hungry rats received the following treatments: LLLLL, SSSSS, LSLSL, and SLSLS, with each letter denoting the magnitude of food reward (large or small) received in each of the five phases of the experiment. Contrast effects were not obtained in the second shift. However, significant positive and negative contrast effects were found in the third shift. The effects started to weaken in the fourth shift, as reflected by a much delayed, albeit significant PCE and a graphical but nonsignificant NCE. The use of multiple shifts to assess the effects of learning and motivation factors on contrast was urged.