Semantic priming in young and older adults: evidence for age constancy in automatic and attentional processes

Automatic and attentional components of semantic priming and the relation of each to episodic memory were evaluated in young and older adults. Category names served as prime words, and the relatedness of the prime to a subsequent lexical decision target was varied orthogonally with whether the target category was expected or unexpected. At a prime-target stimulus-onset asynchrony (SOA) of 410 ms, target words in the same category had faster lexical decision latencies than did different category targets. This effect was not significant at a 1,550-ms SOA and was attributed to automatic processes. Expected category targets had faster latencies than unexpected category targets at the 410-ms SOA, and the magnitude of the effect increased at the 1,550-ms SOA. This effect was attributed to attentional processes. These patterns of priming were obtained for both age groups, but in a surprise memory test older adults had poorer recall of primes and targets. We discuss the implications of these results for the hypothesis that older adults suffer deficits in selective attention and for the related hypothesis that attentional deficits impair semantic processing, which causes memory decrements in old age.     

Response inhibition and avoidance of virtual obstacles during gait in healthy young and older adults

Adjustments of preplanned steps are essential for fall avoidance and require response inhibition. Still, inhibition is rarely tested under conditions resembling daily living. We evaluated the ability of young and older adults to modify ongoing walking movements using a novel precision step inhibition (PSI) task combined with an auditory Stroop task.Healthy young (YA, n = 12) and older (OA, n = 12) adults performed the PSI task at 4 individualized difficulty levels, as a single and dual task (DT). Subjects walked on a treadmill by stepping on virtual stepping stones, unless these changed color during approach, forcing the subjects to avoid them. OA made more failures (40%) on the PSI task than YA (16%), but DT did not affect their performance. In combination with increased rates of omitted Stroop task responses, this indicates a “posture first” strategy. Yet, adding obstacles to the PSI task significantly deteriorated Stroop performance in both groups (the average Stroop composite score decreased by 13% in YA and 27% in OA). Largest deficit of OA was observed in rates of incorrect responses to incongruent Stroop stimuli (OA 35% and YA 12%), which require response inhibition. We concluded that the performance of OA suffered specifically when response inhibition was required.     

Sustained-attention capacity in young and older adults

The sustained-attention capacity of young (21-29 years) and older (65-78 years) adults was examined using a high-event rate digit-discrimination vigilance task presented at three levels of stimulus degradation. Increased stimulus degradation led to a reduction in the hit rate and to a greater decline in hit rate over blocks (increased vigilance decrement). Sensitivity (d') declined over blocks only at the highest level of stimulus degradation. Older adults had a lower hit rate and showed greater vigilance decrement than young adults, particularly when stimuli were highly degraded. However, both age groups showed the same pattern of stability in sensitivity when stimulus degradation was moderate, and sensitivity decrement over time when stimulus degradation was high. The results suggest that the process of sustained allocation of capacity--as reflected in temporal changes in sensitivity--operates similarly in young and older adults.     

Semantic satiation and lexical ambiguity resolution.

This study examines the effects of semantic satiation on lexical ambiguity resolution. On a given trial, participants were presented with a word triad. The first word (e.g., HEART) was presented on average 2.5, 12.5, or 22.5 times, and then participants received 2 new words for relatedness judgments. The first of the two new words was always a homograph (e.g., "ORGAN") and the other word was a related or unrelated pairmate (e.g., "KIDNEY"). In Experiment 1, when blocks of trials were intermixed with concordant (e.g., "HEART-ORGAN-KIDNEY"), discordant (e.g., "PIANO-ORGAN-KIDNEY"), and neutral (e.g., "CEILING-ORGAN-KIDNEY") trials, participants did not produce evidence of semantic satiation. In a second experiment in which only concordant and neutral trials were presented, however, participants did produce evidence of semantic satiation in the concordant condition. Taken together, Experiments 1 and 2 indicate that semantic satiation of the context-appropriate meaning of a homograph may impede ambiguity resolution.     

Self-initiated object-location memory in young and older adults

The present study explored self-initiated object-location memory in ecological contexts, as aspect of memory that is largely absent from the research literature. Young and older adults memorized objects-location associations they selected themselves or object-location associations provided to them, and elaborated on the strategy they used when selecting the locations themselves. Retrieval took place 30 min and 1 month after encoding. The results showed an age-related decline in self-initiated and provided object-location memory. Older adults benefited from self-initiation more than young adults when tested after 30 min, while the benefit was equal when tested after 1 month. Furthermore, elaboration enhanced memory only in older adults, and only after 30 min. Both age groups used deep encoding strategies on the majority of the trials, but their percentage was lower in older adults. Overall, the study demonstrated the processes involved in self-initiated object-location memory, which is an essential part of everyday functioning.     

Implicit and explicit memory in young and older adults

In three experiments, young and older adults were compared on both implicit and explicit memory tasks. The size of repetition priming effects in word completion and in perceptual identification tasks did not differ reliably across ages. However, age-related decrements in performance were obtained in free recall, cued recall, and recognition. These results, similar to those observed in amnesics, suggest that older adults are impaired on tasks which require conscious recollection but that memory which depends on automatic activation processes in relatively unaffected by age.     

Feature memory and binding in young and older adults

Intact memory for complex events requires not only memory for particular features (e.g., item, location, color, size), but also intact cognitive processes for binding the features together. Binding provides the memorial experience that certain features belong together. The experiments presented here were designed to explicate these as potentially separable sources of age-associated changes in complex memory—namely, to investigate the possibility that age-related changes in memory for complex events arise from deficits in (1) memory for the kinds of information that comprise complex memories, (2) the processes necessary for binding this information into complex memories, or (3) both of these components. Young and older adults were presented with colored items located within an array. Relative to young adults, older adults had a specific and disproportionate deficit in recognition memory for location, but not for item or for color. Also, older adults consistently demonstrated poorer recognition memory for bound information, especially when all features were acquired intentionally. These feature and binding deficits separately contribute to what have been described as older adults’ context and source memory impairments.     

Instantiation of general terms in young and older adults

Instantiation of general terms in discourse requires inference from general world knowledge and use of linguistic context to particularize meaning. According to the semantic deficit hypothesis, older adults should be less likely than young adults to generate or to store such inferences. In Experiments 1 and 2 an indirect measure, relatedness judgment, was used to assess immediate comprehension and memory for inferences. In Experiment 3 a direct measure, cued recall, was used to tap memory for inferences. No age differences in immediate or delayed memory were observed in Experiments 1 or 2. In Experiment 3 older adults recalled fewer sentences, but there was no evidence for a specific decrement in storage of inferential material. Older adults are not impaired in ability to draw inferences based on general world knowledge, nor are they more likely than young adults to encode linguistic information in a general, stereotypic fashion.     

Relational frameworks for recall in young and older adults

Recent research indicates the presence of an age-related visual processing deficit, for which the elderly may attempt to compensate through the use of relational information. This hypothesis was tested, using the category superiority effect as a model system. In studies of young adults, the category superiority effect has been shown to be confined to relatively abstract stimulus materials, such as verbal items, and to be absent for pictures. However, it was predicted that a category superiority effect would be present in elderly adults both for verbal and for pictorial stimuli, since the elderly would be expected to utilize category information to compensate for imagerie deficits. This prediction was confirmed, consistent with the hypothesis advanced above. It was further suggested that the establishment of a prior framework for recall, based on relational information, would reduce this effect significantly. This prediction was also confirmed. This research was supported by Grant AGI 1605, National Institute on Aging, and by a grant from the School of Natural Sciences, California State University, Fresno.     

Self-referencing enhances recollection in both young and older adults

Processing information in relation to the self enhances subsequent item recognition in both young and older adults and further enhances recollection at least in the young. Because older adults experience recollection memory deficits, it is unknown whether self-referencing improves recollection in older adults. We examined recollection benefits from self-referential encoding in older and younger adults and further examined the quality and quantity of episodic details facilitated by self-referencing. We further investigated the influence of valence on recollection, given prior findings of age group differences in emotional memory (i.e., “positivity effects”). Across the two experiments, young and older adults processed positive and negative adjectives either for self-relevance or for semantic meaning. We found that self-referencing, relative to semantic encoding, increased recollection memory in both age groups. In Experiment 1, both groups remembered proportionally more negative than positive items when adjectives were processed semantically; however, when adjectives were processed self-referentially, both groups exhibited evidence of better recollection for the positive items, inconsistent with a positivity effect in aging. In Experiment 2, both groups reported more episodic details associated with recollected items, as measured by a memory characteristic questionnaire, for the self-reference relative to the semantic condition. Overall, these data suggest that self-referencing leads to detail-rich memory representations reflected in higher rates of recollection across age.     

Self-initiated spatial working memory in young and older adults

The age-related decline in working memory (WM) has been studied extensively. Yet, research has focused mainly on one aspect of memory, in which older adults memorised information provided to them, neglecting the frequent everyday behaviour in which memory is self-initiated (SI), meaning that individuals memorise information they selected themselves. The present study used a modified spatial span task in which young and older adults memorised spatial sequences they constructed themselves, or random sequences provided to them. The results revealed that young and older adults carefully planned and constructed structured spatial sequences, by minimising distances between successive locations, and by selecting sequences with fewer path crossings and with more linear shapes. Older adults constructed sequences that were even more structured in some aspects. Young and older adults benefited from self-initiation to the same extent, showing similar age-related declines in SI and provided spatial WM. Overall, the study shows that older adults have access to metacognitive knowledge on the structure of efficient WM representations that benefit accuracy, and shows that older adults can use strategic encoding processes efficiently when encoding is SI. More generally, SI WM explores an important aspect of behaviour, demonstrating how older adults shape their environment to facilitate cognitive functioning.     

Self-reference enhances relational memory in young and older adults

The present study investigated the influence of self-reference on two kinds of relational memory, internal source memory and associative memory, in young and older adults. Participants encoded object–location word pairs using the strategies of imagination and sentence generation, either with reference to themselves or to a famous other (i.e., George Clooney or Oprah Winfrey). Both young and older adults showed memory benefits in the self-reference conditions compared to other-reference conditions on both tests, and the self-referential effects in older adults were not limited by low memory or executive functioning. These results suggest that self-reference can benefit relational memory in older adults relatively independently of basic memory and executive functions.     

Antimnemonic effects of schemas in young and older adults

Schema-consistent material that is aligned with an individual’s knowledge and experience is typically more memorable than abstract material. This effect is often more extreme in older adults and schema use can alleviate age deficits in memory. In three experiments, young and older adults completed memory tasks where the availability of schematic information was manipulated. Specifying nonobvious relations between to-be-remembered word pairs paradoxically hindered memory (Experiment 1). Highlighting relations within mixed lists of related and unrelated word pairs had no effect on memory for those pairs (Experiment 2). This occurred even though related word pairs were recalled better than unrelated word pairs, particularly for older adults. Revealing a schematic context in a memory task with abstract image segments also hindered memory performance, particularly for older adults (Experiment 3). The data show that processing schematic information can come with costs that offset mnemonic benefits associated with schema-consistent stimuli.     

Relational frameworks for recall in young and older adults

Recent research indicates the presence of an age-related visual processing deficit, for which the elderly may attempt to compensate through the use of relational information. This hypothesis was tested, using the category superiority effect as a model system. In studies of young adults, the category superiority effect has been shown to be confined to relatively abstract stimulus materials, such as verbal items, and to be absent for pictures. However, it was predicted that a category superiority effect would be present in elderly adults both for verbal and for pictorial stimuli, since the elderly would be expected to utilize category information to compensate for imagerie deficits. This prediction was confirmed, consistent with the hypothesis advanced above. It was further suggested that the establishment of a prior framework for recall, based on relational information, would reduce this effect significantly. This prediction was also confirmed. This research was supported by Grant AGI 1605, National Institute on Aging, and by a grant from the School of Natural Sciences, California State University, Fresno.     

Trait impulsiveness and executive function in healthy young adults

Performance-based neuropsychological tests are often used to assess planning and impulse control, but the extent to which these measures reflect trait impulsiveness or specific dimensions of trait impulsiveness is not clear. This study used the Barratt Impulsiveness Scale-11 (BIS-11; [Patton, J. H., Stanford, M. S., & Barratt, E. S. (1995). Factor structure of the Barratt Impulsiveness Scale. Journal of Clinical Psychology, 51, 768–774.]) to examine the relationship between various dimensions of trait impulsiveness and performance on several executive function tests in healthy young adults. Total BIS-11 scores correlated with performance on measures of planning and impulse control. Higher non-planning impulsiveness scores, which indicate poorer self-control and lower cognitive complexity, correlated most strongly with performance on a maze test that measures planning and impulse control (r = .58). These results provide support for the convergent validity of pencil-and-paper maze-based measures of planning and impulse control.     

Both young and older adults discount suggestions from older adults on a social memory test

In the present study, we examined the impacts of participant age and confederate age on social memory processes. During a collaborative recall phase, young and older adult participants were exposed to the erroneous memory reports of a young or an older adult confederate. On a subsequent individual recall test, young and older adult participants were equally likely to incorporate the confederates’ erroneous suggestions into their memory reports, suggesting that participant age had a minimal effect on social memory processes. However, confederate age did have a marked effect: Young adult participants were less likely to incorporate misleading suggestions from older adult confederates and less likely to report “remembering” items suggested by older adult confederates. Critically, older adult participants were also less likely to incorporate misleading information from fellow older adult confederates. Both young and older adult participants discounted older adult confederates’ contributions to a memory test.     

Repetition blindness and homophone blindness in young and older adults

We tested age effects on repetition blindness (RB), defined as the reduced probability of reporting a target word following presentation of the same word in a rapidly presented list. We also tested age effects on homophone blindness (HB), in which the first word is a homophone of the target word rather than a repeated word. Thirty young and 28 older adults viewed rapidly presented lists of words containing repeated, homophone, or unrepeated word pairs and reported all of the words immediately after each list. Older adults exhibited a greater degree of RB and HB than young adults using a conditional scoring method that provides certainty that blindness has occurred. The existence of RB and HB for both age groups, and increased blindness for older compared to young adults, supports predictions of a binding theory that has successfully accounted for a wide range of phenomena in cognitive aging.     

Working-memory capacity and reading comprehension in young and older adults

Summary This study investigates the role of working-memory capacity in reading comprehension in young and older subjects. A task yielding separate measures for processing and storage components was used to assess working-memory capacity. A French version of the Nelson-Denny test was administered as a measure of abilities that underlie reading comprehension. In the working-memory task, recall performances were lower in older subjects. Nevertheless, the intercorrelations suggested that the age-related impairment was probably linked to the processing component. Mean scores on the reading-comprehension test did not differ between groups. However, scores were correlated with processing time on the working-memory task in younger subjects, but with storage capacity in older subjects.     

Emotional influences on sit-to-walk in healthy young adults

The purpose of this study was to investigate influences of emotional feelings on sit-to-walk (STW). Eighteen healthy young adults performed STW while feeling sadness, anger, joy and neutral emotion. Emotions were elicited using an autobiographical memories task. We used an optoelectronic motion capture system to collect motion data and assessed kinematics of STW. Emotion-related differences in STW kinematics were consistent with differences in movement speed. Compared to neutral emotion, sadness was associated with increased STW duration and phase durations, decreased peak forward and vertical center-of-mass (COM) velocity, increased drop in forward COM velocity, and increased forward and vertical normalized jerk score (NJS). Anger and joy were associated with decreased STW duration and phase durations, increased peak forward and vertical COM velocity, decreased drop in forward COM velocity, and decreased forward and vertical NJS compared to neutral emotion. Findings suggest that emotional feelings affect movement speed, hesitation, and movement smoothness during STW.