The effect of associations and expectations on lexical decision making in normals, alcoholics, and alcoholic Korsakoff patients

This study examined whether patients with Korsakoff's disease suffer from increased PI during encoding. The ability of the name of one category, e.g., BIRD, to prime the processing of members of another category, e.g., BODY PARTS, in a lexical decision task was used to assess the amount of PI during encoding. This task required a subject to inhibit the normal associations to BIRD. Young normals (25 years), older normals (48 years), alcoholics (45 years), and alcoholic Korsakoff patients (59 years) performed two lexical decision tasks. In the first experiment, the appearance of the neutral prime XXX 750 msec before the probe signaled that if the probe was a word, there was a 75% chance that it was from a particular category (e.g., BODY PARTS). The prime facilitated reaction time for words from the expected category for all four groups. The prime slowed reaction time for words that were not from the expected category for the young normals but did not influence reaction time for unexpected words for the three older groups. The second experiment was identical to the first except that a category word was used as the prime. The category word used as the prime was unrelated to the category of the words that were likely to follow it. For example, BIRD might be used to signal the likelihood that the word would be from the category, BODY PARTS. Again, young normals were slower to respond to unexpected probe words, but the three older groups were not. Again, the prime facilitated reaction time for expected words for the young normals, older normals, and alcoholics. However, the word prime did not facilitate reaction time for expected words for the alcoholic Korsakoff patients. That the word prime did not facilitate reaction time for the Korsakoff patients was viewed as evidence that they were unable to inhibit its normal associations and were more sensitive to PI from these associations than the other subjects.