Can subjects avoid creating false memories as outlined in Roediger and McDermott's (1995) false recognition paradigm if they are forewarned about this memory illusion? We presented subjects with semantically related word lists, followed by a recognition test. The test was composed of studied words, semantically related nonstudied words (critical lures), and unrelated nonstudied words. One group of subjects was uninformed about the false recognition effect, a second group was urged to minimize all false alarms, and a third group was forewarned about falsely recognizing critical lures. Compared with the uninformed and cautious subjects, the forewarned subjects reduced their false alarm rate for critical lures, and they made remember and know judgments equally often for recognized studied words and critical lures. But forewarning did not eliminate the false recognition effect, as these subjects and those in the other groups made numerous false recognitions in this task.

Based on his finding that subjects can show an affective preference to previously seen stimuli that they fail to recognize, Zajonc (1980) claimed that affective processing operates separately from cognitive processing. Over four experiments, we replicated and extended the finding that mere exposure to a briefly presented stimulus can increase positive affect through familiarity without enhancing the recognition of that stimulus. Among our findings, lateralized presentation of the irregular polygon stimuli showed that affect judgments were best for stimuli presented in the right visual field (left hemisphere), whereas recognition judgments were best for stimuli presented in the left visual field (right hemisphere). These effects were found only when the study stimuli were shown for 2 msec and were unmasked or for 5 msec and were pattern masked; when the stimuli were shown for 5 msec and were energy masked, target selection by affect or recognition was not greater than chance. These data, along with results from contingency probability analyses, indicate that affect and recognition judgments are different. Rather than viewing the difference between affect and recognition in terms of different features that might reside in the stimulus, the difference in judgments may reflect the manner in which a stimulus representation has been accessed. When viewed in terms of different retrieval processes that access different information, target selection by affect in the absence of recognition can be interpreted in terms of existing models of recognition memory.

Subjects exposed to lists of semantically related words falsely remember nonstudied words that are associated with the list items (e.g., Deese, 1959; Roediger & McDermott, 1995). To determine if subjects would demonstrate this false memory effect if they were unable to recognize the list items, we presented lists of semantically related words with or without a concurrent memory load at rates of 2 s, 250 ms, or 20 ms per word (Experiment 1, between-subjects design) and 2 s or 20 ms per word (Experiment 2, within-subjects design). We found that the subjects falsely recognized semantically related nonstudied words in all conditions, even when they were unable to discriminate studied words from unrelated nonstudied words. Recognition of list items was unnecessary for the occurrence of the false memory effect. This finding suggests that this memory illusion can be based on the nonconscious activation of semantic concepts during list presentation.

Previous research has found that repeated exposure to briefly presented visual stimuli can increase the positive affect for the stimuli without enhancing their recognition. Subjects could discriminate target and distractor shapes by affective preference in the absence of recognition memory. This study examined this phenomenon as a function of stimulus exposure duration. Over exposure durations of 0, 2, 8, 12, 24, and 48 ms, the functions for affect and recognition judgments exhibited different temporal dynamics. Target selection by affect was possible at very brief exposures and was influenced little by increasing durations; target selection by recognition required longer stimulus exposures and improved with increasing durations. Affective discrimination of stimuli that are not recognized is a reliable phenomenon, but it occurs only within a narrow band of time. This parametric study has specified the relationship between exposure duration and affect and recognition judgments and has located that temporal window.

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