Adult age differences in short-term memory and subsequent long-term memory for actions.

Short-term memory for actions was investigated for young adult and elderly adult subjects with the Brown-Peterson procedure at retention intervals of 0 and 15 s. The short-term memory trials were followed by the long-term recall of the prior to-be-remembered actions. The 15-s retention interval was filled either with no activity or with 1 of 3 different interfering activities. Verbal interference had little effect on short-term memory at either age level. Actions performed in the interval either by the subjects or by the experimenter produced significantly lower recall scores at each age level, with the decrement being more pronounced for the elderly than for the young subjects. The long-term memory results indicated that successful short-term recall enhanced later long-term recall, regardless of age level.     

Regularization in short-term memory for serial order

Previous research has shown that short-term memory for serial order can be influenced by background knowledge concerning regularities of sequential structure. Specifically, it has been shown that recall is superior for sequences that fit well with familiar sequencing constraints. The authors report a corresponding effect pertaining to serial recall errors. Undergraduate participants performed immediate serial recall on sequences of pseudowords generated on the basis of an artificial grammar. After extensive experience with this material, recall errors displayed a bias toward regularizing responses, response sequences more probable, with respect to the artificial grammar, than the originally presented stimulus sequence. This regularization effect squares well with recent trace redintegration and Bayesian models of serial recall, and appears to represent an analog of the schema-based error patterns observed in other domains of memory.     

Adult age differences in short-term forgetting

Two experiments are reported in which young and old adults performed in a Brown-Peterson task. In the first experiment young adults recalled with greater accuracy than old adults and the difference between age groups was greater in delayed than in immediate recall. Performance varied inversely with interpolated task difficulty in the delayed recall condition, but this effect did not interact with age. In the second experiment an attempt was made to equate immediate recall performances of old and young adults to determine if age differences in the rate of forgetting are independent of age differences in registration. Each participant was pre-tested to determine the number of stimulus repetitions needed to achieve a minimum of 83% correct in immediate serial recall of 6-letter sequences. The number of repetitions an individual required in pre-testing was then used in a subsequent Brown-Peterson task. No significant age differences in delayed recall were obtained when immediate recall differences were minimized by differential repetition of to-be-remembered sequences. The results of these experiments suggest that age differences in forgetting rates arise from age-related differences in encoding and storage.     

Syntax and serial recall: How language supports short-term memory for order

The extent to which familiar syntax supports short-term serial recall of visually presented six-item sequences was shown by the superior recall of lists in which item pairs appeared in the order of “adjective–noun” (items 1–2, 3–4, 5–6)—congruent with English syntax—compared to when the order of items within pairs was reversed. The findings complement other evidence suggesting that short-term memory is an assemblage of language processing and production processes more than it is a bespoke short-term memory storage system.     

Adult age differences in working memory

Two experiments were conducted to determine whether adult age differences in working memory should be attributed to less efficient processing, a smaller working memory storage capacity, or both. In Experiment 1, young, middle-age, and older adults solved three addition problems before giving the answers to any. Older adults added as well as young and middle-age adults but showed a more pronounced serial position curve across the three problem positions. In Experiment 2, young and older adults constructed linear orderings (e.g., ABCD) from pairwise information presented in sentences (e.g., BC). Manipulations involving processing (e.g., type of sentence) did not interact with age differences, but those involving storage capacity (e.g., ordering length) did. All main effects and interactions support the hypothesis of a smaller storage capacity but do not rule out some processing deficit in older adults.     

Adult age differences in working memory

Active and passive measures of short-term memory over a large segment of the adult life span were compared. Two hundred twenty-eight volunteers, aged 30 to 99 years, performed the digit span forward and backward task, the Peterson-Peterson task, and a new working memory task in which active manipulation of information is emphasized. Age differences were slight for passive tasks. For the working memory task, significant declines were found between the ages of 60 to 69 and 70+ years. It is suggested that the age differences may be due to a decrease in the flexibility with which processing changes are made.     

Short-term memory for serial order: a recurrent neural network model

Despite a century of research, the mechanisms underlying short-term or working memory for serial order remain uncertain. Recent theoretical models have converged on a particular account, based on transient associations between independent item and context representations. In the present article, the authors present an alternative model, according to which sequence information is encoded through sustained patterns of activation within a recurrent neural network architecture. As demonstrated through a series of computer simulations, the model provides a parsimonious account for numerous benchmark characteristics of immediate serial recall, including data that have been considered to preclude the application of recurrent neural networks in this domain. Unlike most competing accounts, the model deals naturally with findings concerning the role of background knowledge in serial recall and makes contact with relevant neuroscientific data. Furthermore, the model gives rise to numerous testable predictions that differentiate it from competing theories. Taken together, the results presented indicate that recurrent neural networks may offer a useful framework for understanding short-term memory for serial order.     

Adult age differences in temporal and item memory

Three experiments tested whether the relationship between age differences in temporal and item memory depends on the degree to which the item memory measure relies on memory for context. The authors predicted a stronger relationship of temporal memory to free recall than to recognition memory. Results showed that age differences in temporal memory could be eliminated after controlling for free recall but not recognition memory performance. Under some conditions recognition memory accounted for a significant portion of age-related variance in temporal memory. These results challenge past research that has interpreted age differences in temporal and item memory as independent and suggest that a generalized decline in context memory may underlie reduced performance in older adults on all types of memory tests.     

Adult age differences in explanations and memory for behavioral information

Age differences in the effects of knowledge-based expectations on both the use of integrative memory processes and recall were examined. In the context of an impression-formation task, young and older adults were presented with lists containing behaviors that varied in consistency with attributed personality traits. Younger adults recalled trait-inconsistent behaviors better than consistent ones, but older adults exhibited no such consistency effect. The age difference in performance was related to the younger adults' spontaneously producing more explanations for inconsistent behaviors. Explanations are assumed to facilitate access to such information by establishing associations with other behavioral information residing in memory. When age differences in the use of explanation-based processing were controlled, the age differences in the effects of consistency on memory were eliminated.     

Serial reconstruction of order and serial recall in verbal short-term memory

We carried out a series of experiments on verbal short-term memory for lists of words. In the first experiment, participants were tested via immediate serial recall, and word frequency and list set size were manipulated. With closed lists, the same set of items was repeatedly sampled, and with open lists, no item was presented more than once. In serial recall, effects of word frequency and set size were found. When a serial reconstruction-of-order task was used, in a second experiment, robust effects of word frequency emerged, but set size failed to show an effect. The effects of word frequency in order reconstruction were further examined in two final experiments. The data from these experiments revealed that the effects of word frequency are robust and apparently are not exclusively indicative of output processes. In light of these findings, we propose a multiple-mechanisms account in which word frequency can influence both retrieval and preretrieval processes.     

Relations between vocabulary development and verbal short-term memory: The relative importance of short-term memory for serial order and item information

Although many studies have shown an association between verbal short-term memory (STM) and vocabulary development, the precise nature of this association is not yet clear. The current study reexamined this relation in 4- to 6-year-olds by designing verbal STM tasks that maximized memory for either item or serial order information. Although empirical data suggest that distinct STM processes determine item and serial order recall, these were generally confounded in previous developmental studies. We observed that item and order memory tasks were independently related to vocabulary development. Furthermore, vocabulary development was more strongly associated with STM for order information in 4- and 6-year-olds and with STM for item information in 5-year-olds. These data highlight the specificity of verbal STM for serial order and item information and suggest a causal association between order STM processes and vocabulary development, at least in 4- and 6-year-olds.     

Adult age differences in memory for massed and distributed repeated actions

Adult age differences in memory for actions were investigated in 2 experiments in which actions were repeated with massed or distributed spacing. In Experiment 1, subjects received a mixed series of actions, half performed once, the others twice, with repetitions either massed or distributed. Young subjects recalled more actions than did the elderly, and more distributed actions were recalled than massed actions. However, the Age X Spacing interaction was not significant. A probable inhibitory mechanism with a mixed list was avoided in Experiment 2 by use of unmixed series. Actions were performed once only, twice only in massed repetitions, or twice only in distributed repetitions. The age difference was significant, and more actions were recalled in the distributed condition than in either of the other conditions, the results of which did not differ from one another. The Age X Conditions interaction was negligible. These results imply that elderly subjects are as likely as young subjects to encode contextual information while performing actions.     

Multiple roles for time in short-term memory: evidence from serial recall of order and timing

Three experiments are reported that examine the relationship between short-term memory for time and order information, and the more specific claim that order memory is driven by a timing signal. Participants were presented with digits spaced irregularly in time and postcued (Experiments 1 and 2) or precued (Experiment 3) to recall the order or timing of the digits. The primary results of interest were as follows: (a) Instructing participants to group lists had similar effects on serial and timing recall in inducing a pause in recall between suggested groups; (b) the timing of recall was predicted by the timing of the input lists in both serial recall and timing recall; and (c) when the recall task was precued, there was a tendency for temporally isolated items to be more accurately recalled than temporally crowded items. The results place constraints on models of serial recall that assume a timing signal generates positional representations and suggest an additional role for information about individual durations in short-term memory.     

Adult age differences in memory for schema-consistent and schema-inconsistent objects in a real-world setting

The present study examined age-related differences in the inconsistency effect, in which memory is enhanced for schema-inconsistent information compared to schema-consistent information. Young and older adults studied schema-consistent and schema-inconsistent objects in an academic office under either intentional or incidental encoding instructions, and were given two recognition tests either immediately or after 48 hr: A yes/no item recognition test that included modified remember/know judgments and a token recognition test that required determining whether an original object was replaced with a different object with the same name. Young and older adults showed equivalent inconsistency effects in both item and token recognition tests, although older adults reported phenomenologically less rich memories of schema-inconsistent objects relative to young adults. These findings run counter to previous reports suggesting that aging is associated with processing declines at encoding that impair memory for details of schema-inconsistent or distinctive events. The results are consistent with a retrieval-based account in which age-related difficulties in retrieving contextual details can be offset by environmental support.     

Oscillator-based memory for serial order

A computational model of human memory for serial order is described (OSCillator-based Associative Recall [OSCAR]). In the model, successive list items become associated to successive states of a dynamic learning-context signal. Retrieval involves reinstatement of the learning context, successive states of which cue successive recalls. The model provides an integrated account of both item memory and order memory and allows the hierarchical representation of temporal order information. The model accounts for a wide range of serial order memory data, including differential item and order memory, transposition gradients, item similarity effects, the effects of item lag and separation in judgments of relative and absolute recency, probed serial recall data, distinctiveness effects, grouping effects at various temporal resolutions, longer term memory for serial order, list length effects, and the effects of vocabulary size on serial recall.     

Adult age differences in binding actors and actions in memory for events

Three experiments provide evidence for an age-related deficit in the binding of actors with their actions. Young and older adults were tested on their memory for a series of events, each involving an actor performing a simple action. Older adults had greater difficulty than did young adults at discriminating old events from novel conjunctions of familiar actors and actions, even when the two groups were equated on memory for each of those features in isolation by using a longer retention interval for young adults. These results are consistent with an age-related associative deficit linked to declines in hippocampal and prefrontal cortical functioning. They further provide evidence that age differences in source monitoring are not limited to speech acts but, rather, generalize to more complex actions. Finally, they provide evidence for age differences in susceptibility to conjunction memory errors, stemming from decreased reliance on recollection and increased reliance on familiarity with increased age. Example videos may be downloaded from www.psychonomic.org/archive.     

Functional characteristics of auditory temporal-spatial short-term memory: evidence from serial order errors

The functional characteristics of auditory temporal-spatial short-term memory were explored in 8 experiments in which the to-be-remembered stimuli were sequences of bursts of white noise presented in spatial locations separated in azimuth. Primacy and recency effects were observed in all experiments. A 10-s delay impaired recall for primacy and middle list items but not recency. This effect was shown not to depend on the response modality or on the incidence of omissions or repetitions. Verbal and nonverbal secondary tasks did not affect memory for auditory spatial sounds. Temporal errors rather than spatial errors predominated, suggesting that participants were engaged in a process of maintaining order. This pattern of results may reflect characteristics that serial recall has in common with verbal and spatial recall, but some are unique to the representation of memory for temporal-spatial auditory events.     

Adult age differences in episodic memory: further support for an associative-deficit hypothesis

This study further tested an associative-deficit hypothesis (ADH; M. Naveh-Benjamin, 2000), which attributes a substantial part of older adults' deficient episodic memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit. First, the results of 2 experiments replicate those observed by M. Naveh-Benjamin (2000) showing that older adults are particularly deficient in memory tests requiring associations. Second, the results extend the type of stimuli (pictures) under which older adults show this associative deficit. Third, the results support an ADH in that older adults show less of an associative deficit when the components of the episodes used are already connected in memory, thereby facilitating their encoding and retrieval. Finally, a group of younger adults who encoded the information under divided-attention conditions did not show this associative deficit.     

Traveling economically through memory space: Characterizing output order in memory for serial order

How do people report the contents of short-term memory when information about order must be retained but items can be retrieved in any order? We report an experiment using an unconstrained reconstruction task in which people can report list items in any order but must place them in their correct serial positions. We found (1) a tendency to report recent items first in immediate but not in delayed reconstruction, (2) a tendency to recall temporally isolated items first, (3) a preference for forward recall order, and (4) a preference for output orders that minimize the length of the path that must be traversed through memory space during retrieval. The results constrain most current models of short-term memory in which retrieval is ballistic and is assumed to run to completion autonomously once initiated.