Changes in open-field behaviour as a result of experimenter manipulation before or after intense shock

Wistar rats received shock at either 25 or 40 days of age. Subgroups received handling and familiarization with the shock apparatus either before or after shock, or at both times. Additional groups received handling without shock or were undisturbed until testing. Open-field ambulation and defecation scores at 60 days indicated that handling was equally effective before and after shock in reducing Ss' subsequent emotionality. This suggests that by the second week of life both conditioned fear and changes in level of arousal are involved in early experience effects. Without qualifiers accounting for conditioning, extinction, and arousal changes occurring during manipulation, general statements relating amount of prior stimulation to later emotionality may be meaningless.