Recently there has been strong interest in the notion that human memory might be separable into components that have been labeled explicit and implicit. In general, explicit memory is believed to be demonstrated in humans via conventional recognition and recall tests, and implicit memory is frequently assessed in priming tests. In priming experiments, a research participant experiences a stimulus (the prime) and later encounters a test with an ambiguous target that is related to the prime. If responding to the target is enhanced by the earlier exposure, priming is considered to have taken place. Research with humans generally shows that an event that evokes no recognition or recall can nevertheless be effective on priming trials in both brain-damaged and unaffected humans.
The research to be reported demonstrated priming in a species of nonhuman animal, the common pigeon (Columba livia). Only three other studies have demonstrated priming in nonhumans, and all contain methodological problems that are corrected in our protocols. In the present research, the target stimulus was a blurred photograph of a picture from one of four categories. The priming event was either a clear depiction of the photograph 30 seconds earlier, or presentation of the blurry photograph itself 24 hours earlier. Presenting a clear photograph of a stimulus (the prime) 30 seconds before presenting a blurry version (the target) increased correct responding to the target. In addition, presenting the blurry photograph 24 hours earlier also increased correct performance. Both results support the existence of priming in pigeon subjects.
Jenna Burke, ’04 Montrose, IA
Sponsor: Suzette Astley