The effects on schedule-induced attack of covarying meal size and spacing

Pigeons were exposed to fixed-time food schedules of 30, 120, and 480 sec with two reinforcer magnitudes at each. Attack behavior against a rear-projected conspecific image was assessed at each interfood/reinforcer magnitude combination. For seven of eight subjects, attack rate was related to interfood interval by an inverted-U or bitonic function. The larger reinforcer magnitude typically induced more attack than the smaller.