Emotion and recognition memory: the discrimination of negative information as an adaptive process

We studied the effect of emotion generated by IAPS (International Affective Picture System) pictures on incidental recognition of these pictures for short retention periods (15 min). Memorization distraction tasks and reaction time tasks were used together with short exposure times (2 seconds per picture) in order to prevent a high recognition rate that would impede testing for the effect of emotion on discrimination parameters (A′) and response bias (B′′D) (ceiling effect). We used 80 pictures representing the medium and high levels of two-dimensional emotional space. The results showed greater discrimination and a more conservative response style to unpleasant and medium arousal level pictures. These pictures produced higher confidence and lower response times in the recognition phase. The results can be explained by the negative content of the pictures and activation level effects on attentional processing and memory, and can be interpreted as a phenomenon that is evolutionarily adaptive.     

Odor recognition without identification

Odors are notoriously difficult to identify, yet an odor can often lead to a sense of recognition, despite an inability to identify it. In the present study, we examined this phenomenon using the recognition-withoutidentification paradigm. Participants studied either odor names alone or odor names that were accompanied by scratch-and-sniff stickers containing their corresponding scents. At test, the participants were presented with blank scratch-and-sniff stickers, half of which corresponded to items that were studied and half of which did not. The participants attempted to identify each test odor, as well as to rate the likelihood that it corresponded to a studied item. In addition, the participants indicated whether they were in a tip-of-the-tongue (TOT) state for a given odor’s name. Odor recognition without identification was found, but only when the participants had actually smelled the test odor at study; it was not found when the participants only studied odor names and were then tested with odors, suggesting that this effect is an episode-specific, perceptually driven phenomenon. Despite this difference, an overall TOT-attribution effect, whereby recognition ratings were higher during TOT states than during non-TOT states, was shown across conditions.     

Exhaustive memory-scanning and familiarity discrimination: Separate mechanisms in recognition memory tasks

Experiment I was a yes-no recognition task with lists of one, two or four items to remember. Each item in the experiment appeared in only one list, and each list was presented only once. One group of subjects performed the task with complex pictures. Their results were incompatible with the hypothesis of exhaustive memory scanning, since the function relating “yes” response latency to list length was not parallel to but steeper than the function for “no” responses. Another group performed the task with words. Their results were consistent with exhaustive memory-scanning. Experiment II was a similar task in which the familiarity was varied of the test items to which the subjects had to respond “no”. That variation affected response latency with pictures but not with words. From these results and from a consideration of relevant neurological data, the hypothesis is advanced that familiarity discrimination and exhaustive memory-scanning are separate mechanisms.     

Odor memory: Review and analysis

We critically review the cognitive literature on olfactory memory and identify the similarities and differences between odor memory and visual-verbal memory. We then analyze this literature using criteria from a multiple memory systems approach to determine whether olfactory memory can be considered to be a separate memory system. We conclude that olfactory memory has a variety of important distinguishing characteristics, but that more data are needed to confer this distinction. We suggest methods for the study of olfactory memory that should make a resolution on the separate memory system hypothesis possible while simultaneously advancing a synthetic understanding of olfaction and cognition.     

Odor memory: taking stock

This review discusses the state of knowledge in odor memory within the framework of mainstream memory research. Experimental findings are structured around prevailing theoretical distinctions in the study of memory proper, including semantic-episodic memory and implicit-explicit memory. Unaided odor-identification performance is found to be approximately 40%-50% of the total stimulus set presented to Ss, although performance approaches the limit of memorial discrimination if Ss are given label training with feedback. Odor identification is conceptualized as a task with 3 major components and where performance falls on a continuum ranging from nonverbal feelings of familiarity to specific object names. Odor recognition is shown to be relatively stable over long retention intervals, and more than 1 explanation can account for this effect. It is also suggested that name recognition may contribute to the results obtained in odor-recognition experiments. Several possible avenues for future research on both explicit and implicit memory for odors are mentioned. It is concluded that although much is known already about memory for odors, many questions still remain unanswered or unasked.     

The effect of variations of emotional expressions on mnemonic discrimination and traditional recognition memory

Face recognition occurs when a face is recognised despite changes between learning and test exposures. Yet there has been relatively little research on how variations in emotional expressions influence people’s ability to recognise these changes. We evaluated the ability to discriminate old and similar expressions of emotions (i.e. mnemonic discrimination) of the same face, as well as the discrimination ability between old and dissimilar (new) expressions of the same face, reflecting traditional discrimination. An emotional mnemonic discrimination task with morphed faces that were similar but not identical to the original face was used. Results showed greater mnemonic discrimination for learned neutral expressions that at test became slightly more fearful rather than happy. For traditional discrimination, there was greater accuracy for learned happy faces becoming fearful, rather than those changing from fearful-to-happy. These findings indicate that emotional expressions may have asymmetrical influences on mnemonic and traditional discrimination of the same face.     

The effect of context on discrimination and bias in recognition memory for pictures and words

When the context accompanying a to-be-remembered word is changed between study and test, recognition memory is impaired. The deleterious effect of context change on recognition memory can be viewed as support for encoding specificity theory, semantic theory, or the existence of two bases for recognition. A fourth possible interpretation, examined here, is that the effect of context change on recognition memory is due to an accompanying change in response bias, rather than a "true" decrease in sensitivity to old and new items. In two experiments, the effect of context change on discrimination and bias in recognition of simple line drawings and their names was examined. Bias was measured using two measures shown by Snodgrass and Corwin (1988) to be theoretically independent of their associated discrimination measures. Context change produced marked conservatism in response bias in both experiments but demonstrated an effect on discrimination in the second experiment only. The shift from a neutral to a conservative response strategy as a result of context change may also be seen in other experiments, in which the same experimental paradigm was used with a variety of stimulus materials. We suggest that the major effect of context manipulation is to produce a change in bias. A stimulus in a familiar environment appears to be more familiar than a stimulus in a strange environment, regardless of its old/new status. In addition, there appears to be a true decrease in discrimination with context change, but this is more difficult to detect. The finding that pictures, which are less polysemous than words, are as affected by context change as words are supports encoding specificity theory over semantic theory.     

Single-item recognition following a verbal discrimination study trial

A verbal discrimination (VD) study phase was followed by a single-item (i.e., one item at a time) test phase. Prior right (R) items from the VD list were found to have higher old-new hit rates on the test phase than prior wrong (W) items. However, prior W items had higher hit rates than prior R items in terms of recognition of their intrapair function. These results were interpreted in terms of a high criterion model whereby an old test item must prossess a large number of frequency units before it is identified as being R. In addition, false recognition effects were demonstrated for new test items that were homophones of prior R items, but not for new test items that were homophones of prior W items. These results were interpreted in terms of a feature analytic extension of frequency theory.     

The effect of dehydroepiandrosterone (DHEA) on recognition memory decision processes and discrimination in postmenopausal women

In this article, the theoretical distinction between recognition memory decision and discrimination processes is used to explore the effect of dehydroepiandrosterone (DHEA) in postmenopausal women. DHEA is an adrenal steroid that diminishes with aging. It has enhanced memory in laboratory animals. An 8-week placebo-controlled, double-blind experiment in which 30 women (ages 39–70) received a 50-mg/day oral dose of DHEA for 4 weeks demonstrated that DHEA made subjects more conservative (i.e., less likely to call test items “old”) in their recognition memory decisions and enhanced recognition memory discrimination for items presented briefly. The former result may reflect an empirical regularity (Hirshman, 1995) in whichrecent strong memory experiences make participants more conservative. The latter result may reflect the effect of DHEA on visual perception, with consequent effects on memory. These results suggest the methodological importance of focusing on decision processes when examining the effects of hormones on memory.     

Odor recognition and identification: effect of labels over time

The effect of labels on recognition and identification of odors over time was assessed. 30 men and 30 women were presented 20 odors; half of the participants were also told a name for the odor as a label. Five min. and 60 min. later, all participants were given 20 odors (10 from the original set, 10 new) and asked whether each odor was new or old (odor recognition). The group given labels was also asked to recall the label provided (odor identification). Analysis indicated a significant effect of time on recognition. Significantly more odors were recognized at 5 min. than 60 min. The effect of label was also significant, with recognition being better for the Label condition than the No-Label condition. As for odor identification, women identified more labels than did men. Overall, odor recognition was better with labels soon after exposure, and the women were better at remembering the labels than the men.     

Odor recognition: familiarity, identifiability, and encoding consistency

The investigation examined the association between the perceived identity of odorous stimuli and the ability to recognize the previous occurrence of them. The stimuli comprised 20 relatively familiar odorous objects such as chocolate, leather, popcorn, and soy sauce. Participants rated the familiarity of the odors and sought to identify them. At various intervals up to 7 days after initial inspection, the participants sought to recognize the odors among sets of distractor odors that included such items as soap, cloves, pipe tobacco, and so on. The recognition response entailed a confidence rating as to whether or not an item had appeared in the original set. At the time of testing, the participants also sought to identify the stimuli again. The results upheld previous findings of excellent initial recognition memory for environmentally relevant odors and slow forgetting. The results also uncovered, for the first time, a strong association between recognition memory and identifiability, rated familiarity, and the ability to use an odor label consistently at inspection and subsequent testing. Encodability seems to enhance rather than to permit recognizability. Even items identified incorrectly or inconsistently were recognized at levels above chance.     

Environmental context-dependent recognition memory using a short-term memory task for input

Although many studies have demonstrated that recall is better when tested in the learning environmental context (EC) than in a new EC, almost all of the studies have failed to find EC-dependent memory when recognition was used to measure memory. Evidence of EC-dependent recognition, however, was found in the three experiments of the present study, in which an incidental short-term memory task was used for input of learned material. The results suggest that type of processing during input is a predictor of context-dependent recognition; material studied for a long-term memory test is not susceptible to background context effects, whereas material merely maintained for a short-term memory test is more apt to lead to EC-dependent recognition.     

Event-related potentials and recognition memory

According to dual-process models, recognition memory is supported by distinct retrieval processes known as familiarity and recollection. Important evidence supporting the dual-process framework has come from studies using event-related brain potentials (ERPs). These studies have identified two topographically distinct ERP correlates of recognition memory--the "parietal" and "mid-frontal" old/new effects--that are dissociated by variables that selectively modulate recollection and familiarity, respectively. We evaluate the extent to which ERP data support dual-process models in light of the proposal that recollection is a continuous rather than a discrete memory process. We also examine the claim that the putative ERP index of familiarity is a reflection of implicit rather than explicit memory. We conclude that ERP findings continue to offer strong support for the dual-process perspective.     

Support for a continuous (single-process) model of recognition memory and source memory

Does memory retrieval occur in a continuous or an all-or-none manner? The shape of the receiver operating characteristic (ROC) has been used to answer this question, with curvilinear and linear memory ROCs indicating continuous and all-or-none retrieval processes, respectively. Signal detection models (e.g., the unequal variance model) correspond to a continuous retrieval process, whereas threshold models (including the multinomial model and the recollection component of the dual-process model) correspond to an all-or-none process. In studies of source memory, Slotnick et al. (2000) and others have observed curvilinear ROCs (supporting the unequal variance model), whereas Yonelinas (1999) observed linear ROCs (supporting the dual-process model). We resolve these seemingly inconsistent results, showing that source memory ROCs are naturally curvilinear but can appear linear when nondiagnostic source information is included in the analysis. Furthermore, the unequal variance model accounted for both recognition memory and source memory ROCs, supporting a continuous process of memory retrieval.     

Human recognition memory: a cognitive neuroscience perspective

For many years the cognitive processes underlying recognition memory have been the subject of considerable interest in experimental psychology. To account for a broad range of behavioral findings, psychologists have put forward a variety of 'dual-process' models, all of which propose that recognition memory is supported by two forms of memory - familiarity and recollection - that differ in their speed of operation and the specificity of the retrieved information. More recently, the dual-process framework has been extended to encompass findings from studies investigating the neural basis of recognition memory. Results from neuropsychological, ERP and functional neuroimaging studies can be accommodated within the framework, and suggest that familiarity and recollection are supported by distinct neural mechanisms.     

Measuring recognition memory.

Recent years have seen an expanded interest in recognition memory tasks. This resurgence of interest has also renewed concerns with measurement problems. Comparing 4 models of recognition memory, Snodgrass and Corwin (1988) found that measures of bias from the distribution-free (nonparametric) model were inadequate. However, their analysis was based on bias measures that can be shown a priori to be nonindependent of discrimination. This article traces the history of the nonparametric model and develops a better measure of bias. The consequence of developing this better measure is that the nonparametric model deserves serious consideration.     

Stimulus-form effectsin recognition memory

In two experiments, recognition memory was tested using memorized lists of items containing from 2 to 32 nominal concepts. Stimulus form was manipulated by using the names of the items on word trials and outline drawings of the items on picture trials. In terms of an information processing stage model of recognition memory, stimulus form affected only an identification or encoding stage of processing. Subsequent memory-search, decision, and response processes were largely the same for all stimuli once the words or pictures were encoded. The results are consistent with the hypothesized role of stimulus form in processes underlying long-term recognition. However, our results are inconsistent with those of a number of studies involving stimulus-form effects in short-term recognition memory.