Trace autoshaping: Acquisition, maintenance, and path dependence at long trace intervals.

The pigeon's tendency to acquire and maintain signal-directed key pecking under a trace conditioning procedure was parametrically examined. In Experiment 1, the percentage of CS trials with a key peck response was a decreasing function of the trace interval for separate groups of pigeons. The majority of subjects acquired signal-directed key pecking with trace intervals as long as 36 sec. In Experiment 2, differential maintenance of key pecking occurred across trace intervals in a within-subject procedure. Maintenance of key pecking at 36- and 60-sec trace intervals was path dependent in that responding depended on the subject's performance under the preceding trace interval.