Fig. 1.

Mean (± SEM) start latency, run time, and retreats for animals running an alley for a single daily injection of 1.0 mg/kg/inj i.v. cocaine. Data are expressed as three-day averages to smooth variability across trials. Note that while animals initiate trials with progressively shorter start latencies as testing continued, there are concurrent increases in run times and approach-avoidance retreat responses.