USES OF VISION BY RATS IN PLAY FIGHTING AND OTHER CLOSE-QUARTER SOCIAL INTERACTIONS

Enucleated juvenile rats were compared to sighted juveniles, and teste d over six trials. In some of these trials, the vibrissae were clipped and the test chamber was flooded with white noise. Even though the en ucleated rats played, they did so in an atypical manner. They tended t o initiate more playful and other social contacts, and were more likel y to defend themselves if contacted. When they did defend themselves, they adopted behavior patterns that were more likely to evade the part ner's attack. In addition, the enucleated rats were hypersensitive to the partner, being more likely to respond defensively when contacted f urther from the nape (the main play target). All these changes in play fighting by nonsighted rats suggest that the loss of vision leads to motivational changes in activity and reactivity, and so has an indirec t effect on play behavior. In addition, direct evidence is also provid ed to show that vision is used to orient attacks to the nape. When the vibrissae were closely clipped, the sighted rats continued to make di rect attacks on the partner's napes, whereas the nonsighted rats did n ot. Rather, they first contacted some other part of the partner's body and then oriented to the nape. Another test paradigm was used to dete rmine whether vision is used to trigger defensive responses. ?The rats were partially food deprived as adults and were filmed in a food wren ching and dodging situation where one rat was given a food pellet and the other allowed to steal it. Measurement of the distance at initiati on of the lateral swerve away from the approaching partner (i.e., dodg e) showed that when the vibrissae are clipped, the sighted rats contin ued to initiate dodges at the same distance, whereas the nonsighted ra ts could not. Therefore, vision appears to have an active role in orga nizing movement sequences of attack and defense in play fighting and o ther close-quarter interactions.