Recognition without awareness: Encoding and retrieval factors.

The article reports 4 experiments that explore the notion of recognition without awareness using words as the material. Previous work by Voss and associates has shown that complex visual patterns were correctly selected as targets in a 2-alternative forced-choice (2-AFC) recognition test although participants reported that they were guessing. The present experiments sought to extend this earlier work by having participants study words in different ways and then attempt to recognize the words later in a series of 4-alternative forced-choice (4-AFC) tests, some of which contained no target word. The data of interest are cases in which a target was present and participants stated that they were guessing, yet chose the correct item. This value was greater than p = .25 in all conditions of the 4 experiments, demonstrating the phenomenon of recognition without awareness. Whereas Voss and colleagues attributed their findings with kaleidoscope patterns to enhanced processing fluency of perceptual attributes, the main factor associated with different levels of recognition without awareness in the present studies was a variable criterion for the subjective state accompanying selection of the "guess" option, depending on the overall difficulty of the recognition test. We conclude by discussing some implications of the results for the distinction between implicit and explicit memory.

Divided attention improves delayed, but not immediate retrieval of a consolidated memory.

A well-documented dissociation between memory encoding and retrieval concerns the role of attention in the two processes. The typical finding is that divided attention (DA) during encoding impairs future memory, but retrieval is relatively robust to attentional manipulations. However, memory research in the past 20 years had demonstrated that retrieval is a memory-changing process, in which the strength and availability of information are modified by various characteristics of the retrieval process. Based on this logic, several studies examined the effects of DA during retrieval (Test 1) on a future memory test (Test 2). These studies yielded inconsistent results. The present study examined the role of memory consolidation in accounting for the after-effect of DA during retrieval. Initial learning required a classification of visual stimuli, and hence involved incidental learning. Test 1 was administered 24 hours after initial learning, and therefore required retrieval of consolidated information. Test 2 was administered either immediately following Test 1 or after a 24-hour delay. Our results show that the effect of DA on Test 2 depended on this delay. DA during Test 1 did not affect performance on Test 2 when it was administered immediately, but improved performance when Test 2 was given 24-hours later. The results are consistent with other findings showing long-term benefits of retrieval difficulty. Implications for theories of reconsolidation in human episodic memory are discussed.

Production benefits both recollection and familiarity.

In three experiments, we investigated the roles of recollection and familiarity in the production effect--the finding that words read aloud are remembered better than words read silently. Experiment 1, using the remember/know procedure, and Experiment 2, using the receiver operating characteristic procedure, converged in demonstrating that production enhanced both recollection and familiarity. Experiment 3 supported the role of recollection by demonstrating that specific episodic information--that is, whether a word had been studied aloud or silently--was stronger for items studied aloud. These findings fit with an explanation of the production effect as hinging on two factors: greater recollection of distinctive information from the study episode, and more familiarity due to greater attention allocated to the material studied aloud.

A double dissociation of implicit and explicit memory in younger and older adults.

This study examined whether age-related differences in cognition influence later memory for irrelevant, or distracting, information. In Experiments 1 and 2, older adults had greater implicit memory for irrelevant information than younger adults did. When explicit memory was assessed, however, the pattern of results reversed: Younger adults performed better than older adults on an explicit memory test for the previously irrelevant information, and older adults performed less well than they had on the implicit test. Experiment 3 investigated whether this differential pattern was attributable to an age-related decline in encoding resources, by reducing the encoding resources of younger adults with a secondary task; their performance perfectly simulated the pattern shown by the older adults in the first two experiments. Both older and younger adults may remember irrelevant information, but they remember it in different ways because of age-related changes in how information is processed at encoding and utilized at retrieval.

Destination memory impairment in older people.

Older adults are assumed to have poor destination memory-knowing to whom they tell particular information-and anecdotes about them repeating stories to the same people are cited as informal evidence for this claim. Experiment 1 assessed young and older adults' destination memory by having participants tell facts (e.g., "A dime has 118 ridges around its edge") to pictures of famous people (e.g., Oprah Winfrey). Surprise recognition memory tests, which also assessed confidence, revealed that older adults, compared to young adults, were disproportionately impaired on destination memory relative to spared memory for the individual components (i.e., facts, faces) of the episode. Older adults also were more confident that they had not told a fact to a particular person when they actually had (i.e., a miss); this presumably causes them to repeat information more often than young adults. When the direction of information transfer was reversed in Experiment 2, such that the famous people shared information with the participants (i.e., a source memory experiment), age-related memory differences disappeared. In contrast to the destination memory experiment, older adults in the source memory experiment were more confident than young adults that someone had shared a fact with them when a different person actually had shared the fact (i.e., a false alarm). Overall, accuracy and confidence jointly influence age-related changes to destination memory, a fundamental component of successful communication.

The production effect: delineation of a phenomenon.

In 8 recognition experiments, we investigated the production effect-the fact that producing a word aloud during study, relative to simply reading a word silently, improves explicit memory. Experiments 1, 2, and 3 showed the effect to be restricted to within-subject, mixed-list designs in which some individual words are spoken aloud at study. Because the effect was not evident when the same repeated manual or vocal overt response was made to some words (Experiment 4), producing a subset of studied words appears to provide additional unique and discriminative information for those words-they become distinctive. This interpretation is supported by observing a production effect in Experiment 5, in which some words were mouthed (i.e., articulated without speaking); in Experiment 6, in which the materials were pronounceable nonwords; and even in Experiment 7, in which the already robust generation effect was incremented by production. Experiment 8 incorporated a semantic judgment and showed that the production effect was not due to "lazy reading" of the words studied silently. The distinctiveness that accrues to the records of produced items at the time of study is useful at the time of test for discriminating these produced items from other items. The production effect represents a simple but quite powerful mechanism for improving memory for selected information.

Recollection and familiarity for public events in neurologically intact older adults and two brain-damaged patients.

Despite extensive investigations of the role of recollection and familiarity on laboratory-acquired memories, there is a dearth of such research on memories formed in real life settings. We used the Remember/Know paradigm to investigate the relative contribution of recollection and familiarity processes to memory of public historical events reported in the media across the life span of two groups of neurologically intact older adults (old-old: 74-85, young-old: 58-69) and on two patients with brain damage. First, in neurologically intact participants, recollection rates decreased as a function of time elapsed since the event occurred, at a significantly higher rate than the corresponding decrease in familiarity or global memory. Second, consistent with the hypothesis that memories become increasingly semantic as they age, and that recollection is selectively impaired in older adults, across decades, old-old participants exhibited lower recollection, but not familiarity, relative to young-old participants. Finally, as a demonstration of how this procedure may be applied to studies of clinical populations, we tested two patients, one with medial temporal lesions and another with relative sparing of the medial temporal lobes, but with anterior temporal damage. We found that recollection was disproportionately impaired relative to familiarity across most of the life span in the patient with medial temporal lesions severely while recollection was relatively intact in the patient with anterior lateral temporal damage. We discuss the present results in the context of neuroanatomical and process-oriented theories of how memories age.

Destination memory: stop me if I've told you this before.

Everyone has recounted a story or joke to someone only to experience a nagging feeling that they may already have told this person this information. Remembering to whom one has told what, an ability that we term destination memory, has been overlooked by researchers despite its important social ramifications. Using a novel paradigm, we demonstrate that destination memory is more fallible than source memory--remembering the person from whom one has received information (Experiment 1). In Experiments 2 and 3, we increased and decreased self-focus, obtaining support for a theoretical framework that explains relatively poor destination memory performance as being the result of focusing attention on oneself and on the processes required to transmit information. Along with source memory, destination memory is an important component of episodic memory that plays a critical role in social interactions.