Overshadowing between two contextual stimuli in rats

The purpose of this experiment was to investigate whether overshadowing occurred between two contextual stimuli (light and tone) in Pavlovian conditioning of rats. Thirty-two albino rats, randomly assigned to four groups, were individually placed in a chamber, in which light, tone or both served as contextual stimuli. A single electric shock (1mA, 2-s) was delivered to the floor during once-a-day 5 min sessions for 5 consecutive days (conditioning phase). The day after finishing-the conditioning phase, each was placed for 5 min in the chamber, and light or tone was presented as a contextual stimulus (test phase). The group of rats exposed to both stimuli during the conditioning sessions but to light only during the test session (LT/L) froze less frequently in the test phase than in the conditioning phase. The other three groups (LT/T, T/T, and L/L) froze in the test phase as frequently as in the conditioning phase. These results suggest that the tone overshadowed a light when both of them were presented together as contextual stimuli of conditioning

Amygdala · Audiology · Classical conditioning · Cognitive psychology · Conditioning · Developmental psychology · Fear conditioning · Measures of conditioned emotional response · Stimulus (psychology) · Tone (literature) · Unconditioned stimulus · Mathematics · Medicine · Memory and Neural Mechanisms · Neuroendocrine regulation and behavior · Neuroscience · Olfactory and Sensory Function Studies · Psychology

• Journal of Comparative and Physiological Psychology

  W K Estes•American Psychologist•1965

  Add to list

• Associative and nonassociative theories of the UCS preexposure phenomenon

  Alan Randich, Vincent M Lolordo•Psychological Bulletin•1979

  Add to list