Some effects of response-independent shocks after unsignaled avoidance conditioning in rats

After extended unsignaled avoidance training, the majority of rats continued frequent responding during long periods when only response-independent shocks were presented. Most responses were shock elicited, i.e., followed immediately after shock. Response rates were directly related to both the frequency and the intensity of response-independent shocks. Responding continued to approximately the same extent, whether shocks were presented at fixed or variable intervals. Few responses were directed toward a second lever in the test chamber, even when the lever previously associated with avoidance was removed. When avoidance was scheduled on the second lever, the rats learned to avoid by operating it. Meanwhile, responding on the first lever became infrequent. Subsequently, when only response-independent shocks were presented, almost all responses occurred upon the lever initially associated with avoidance. Responding that was elicited by response-independent shocks was suppressed by response-dependent (punishment)_shocks of the same intensity. When punishment was withdrawn, recovery of responding occurred. An explanation of the results based upon shock-elicited behaviors is preferred to one stressing unextinguished avoidance responding.     

The effect of shock intensity upon responding under a multiple-avoidance schedule

The effect of two shock intensities (1.00 and 2.00 mA) were studied in the acquisition, maintenance, and extinction of unsignalled avoidance by albino rats. Single and multiple avoidance schedules were employed, with shock intensity being the principal condition that differed between schedule components. The higher shock intensity was generally more effective in producing avoidance. Higher response rates and lower shock rates were observed under high-intensity shock when performance stabilized. When the multiple schedule was introduced, the six rats trained under a single shock intensity all showed poorer performance under the new shock intensity, whether it was higher or lower than the training intensity. Performance under the original shock intensity did not change substantially with the introduction of a different shock intensity in the other multiple schedule component. Performance under the new shock intensity showed gradual improvement with continued exposure to it. All of the rats showed persistent “warm-up”, receiving approximately 40% of the total session shocks in the first one-sixth of the session. The degree of warm-up was unrelated to avoidance shock intensity.     

Hippocampal lesions and pavlovian cardiovascular conditioning

New Zealand albino rabbits received either sham, cortical control, or hippocampal lesions and were subjected to differential Pavlovian conditioning in which tones of different frequencies served as conditional stimuli (CSs), and a brief paraorbital electric shock train served as the unconditional stimulus. Heart rate (HR), blood pressure (BP), and electromyographic (EMG) conditional responses (CRs) were recorded. Animals with cortical and hippocampal damage or animals with cortical damage alone revealed attenuated bradycardiac CRs, but HR CRs of the former two groups did not significantly differ. BP changes were minimal; reliable differences were not obtained between CS+ and CS?. However, these changes consisted of small but reliable depressor responses, which were not affected by either cortical or hippocampal lesions. Few EMG CRs were obtained. These data, combined with those of previous experiments, suggest that forebrain structures may modulate higher level processing of stimulus information, perhaps in terms of assessing the biological significance of such stimulation.     

A comparison of adult women's and men's ascriptions of negative traits to the same and opposite sex

College students (N=135), ranging from 19 to 55 years of age, were studied to determine their sex stereotypes. Results from the present study indicated that adult males were significantly more negative than adult females in their evaluations of both sexes. One possible explanation that may be offered to account for these findings is that current emphasis of female rights may be causing negativistic reactions on the part of males toward both sex groups.     

Behavioral engineering: the use of response priming to improve prescribed self-medication

A major problem in outpatient treatment has been the extreme irregularity with which patients use medication prescribed for them. As a new approach to resolving this problem, a portable operant apparatus was developed based on response priming and escape reinforcement. The apparatus sounded a tone at the time that a pill was to be taken. When the user turned a knob to terminate the tone, the apparatus delivered the pill into the user's hand. The apparatus was evaluated with six normal adults using a medically inert pill. A greater proportion of the pills were taken by each subject when using the special apparatus as compared with the use of a portable alarm timer or the usual wristwatch. These results demonstrate a new approach for increasing the regularity of self-administration of medicines.     

Frequency of attack in shock-elicited aggression as a function of the performance of individual rats

Fighting rates between paired rats were investigated as a function of the probability of attack by a single animal. Animals from stable high-fighting and low-fighting frequency pairs were intermatched to detect individual high-fighting and low-fighting rats. Pairs of high-fighting animals then received saline or different chlorpromazine dosages during successive sessions. Finally, single high-fighting members of each pair also received the different drug dosages. The chief findings were that: (a) rats showing high fighting rates when matched against each other revealed low fighting rates when matched against one, but not the other member of a low-fighting pair; and (b) high-fighting rats decreased their fighting rates as their own or their opponent's chlorpromazine dosage increased. These results indicated that a low rate of fighting on the part of one rat results in a low fighting rate on the part of its opponent.