Semantic short-term memory and its role in sentence processing: a replication

Previous studies have shown that an aphasic patient (AB) with a semantic short-term memory deficit (STM) had difficulties comprehending and producing sentences with structures that demanded the simultaneous retention of several individual word meanings (Martin & Freedman, 2001a, 2001b; Martin & Romani, 1994; Martin, Shelton, & Yaffee, 1994). The present study provides a replication of these findings with an additional case (ML) who shows a striking dissociation between preserved semantic knowledge and disrupted semantic STM. ML performed poorly on comprehension tasks for sentences that required the retention of single word meanings across several intervening words. In contrast, he did not show an effect of intervening words on processing grammatical relations. ML had difficulty producing adjective-noun phrases, though able to produce the individual nouns and adjectives. These findings support the contention that there is a semantic retention capacity, involved in both comprehension and production, that is separate from semantic knowledge representations.     

The contributions of encoding,retention, and recall to the Hebb effect

The article reports an experiment testing whether the Hebb repetition effect—the gradual improvement of immediate serial recall when the same list is repeated several times—depends on overt recall of the repeated lists. Previous reports which suggest that recall is critical confound the recall manipulation with retention interval. The present experiment orthogonally varies retention interval (0 or 9 s) and whether the list is to be recalled after the retention interval. Hebb repetition learning is assessed in a final test phase. A repetition effect was obtained in all four experimental conditions; it was larger for recalled than non-recalled lists, whereas retention interval had no effect. The results show that encoding is sufficient to generate cumulative long-term learning, which is strengthened by recall. Rehearsal, if it takes place in the retention interval at all, does not have the same effect on long-term learning as overt recall.     

Spaced retrieval: absolute spacing enhances learning regardless of relative spacing

Repeated retrieval enhances long-term retention, and spaced repetition also enhances retention. A question with practical and theoretical significance is whether there are particular schedules of spaced retrieval (e.g., gradually expanding the interval between tests) that produce the best learning. In the present experiment, subjects studied and were tested on items until they could recall each one. They then practiced recalling the items on 3 repeated tests that were distributed according to one of several spacing schedules. Increasing the absolute (total) spacing of repeated tests produced large effects on long-term retention: Repeated retrieval with long intervals between each test produced a 200% improvement in long-term retention relative to repeated retrieval with no spacing between tests. However, there was no evidence that a particular relative spacing schedule (expanding, equal, or contracting) was inherently superior to another. Although expanding schedules afforded a pattern of increasing retrieval difficulty across repeated tests, this did not translate into gains in long-term retention. Repeated spaced retrieval had powerful effects on retention, but the relative schedule of repeated tests had no discernible impact.     

Effect of novel experiences on retention of inhibitory avoidance behavior in mice: the influence of previous exposure to the same or another experience

Mice were trained and tested in a step-through inhibitory avoidance task with a 24-h interval between training and testing. At one of several intervals prior to the test session (9 h, 6 h, 3 h, or 6 min), they were given one of the following novel experiences: 4 min in a small Plexiglas box containing an empty water bottle, or 4 min hanging from the wire mesh ceiling of a large Plexiglas box. When given 3 h or 6 min before testing, both novel experiences enhanced retention test performance. The effect was antagonized by naltrexone and mimicked by an administration of beta-endorphin 6 min prior to testing. Thus, the findings are consistent with previous evidence suggesting that the effects of novel experiences on retention test performance are due to an activation of the brain beta-endorphin system. When one of the novel experiences given 3 h or 6 min prior to testing was preceded by the same experience given 6 h earlier retention test performance was not enhanced. Thus, the enhancing effect is obtained only if the experience is novel. Further, an experience given prior to retention testing did not affect performance if either the same or a different experience was given 3 h earlier. This finding is consistent with previous evidence indicating that following a novel experience, the brain beta-endorphin remains unresponsive for several hours. These results provide additional evidence that novel experiences prior to retention testing affect retention performance and provide additional support for the view that the effect may involve the release of beta-endorphin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acquisition and extended retention of a conditioned taste aversion in preweanling rats

The time course of memory decay for infant rats may shed light on the processes responsible for infantile amnesia. A taste aversion conditioning procedure appropriate for both neonatal and adult rats was employed in four experiments to investigate the ontogeny of extended retention. In Experiment 1, rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those rats conditioned when 20 or 60 days old demonstrated significant taste aversions. Experiments 2 and 3 established that rats 14-15 days old and older were able to retain significant taste aversions following a 25-day retention interval. Younger rats did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Experiment 4). These findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident.     

Short-term effects of grade retention on the growth rate of Woodcock-Johnson III broad math and reading scores

We investigated the effects of grade retention in first grade on the growth of the Woodcock-Johnson broad mathematics and reading scores over three years using linear growth curve modeling on an academically at-risk sample. A large sample (n = 784) of first grade children who were at risk for retention was initially identified based on low literacy scores. Scores representing propensity for retention were constructed based on 72 variables collected in comprehensive baseline testing in first grade. We closely matched 97 pairs of retained and promoted children based on their propensity scores using optimal matching procedures. This procedure adjusted for baseline differences between the retained and promoted children. We found that grade retention decreased the growth rate of mathematical skills but had no significant effect on reading skills. In addition, several potential moderators of the effect of retention on growth of mathematical and reading skills were identified including limited English language proficiency and children's conduct problems.     

Using Marginal Structural Modeling for Grade Retention Effects

Vandecandelaere, Vansteelandt, De Fraine, and Van Damme (this issue) described marginal structural modeling (MSM) and used it to estimate the effects of a time-varying intervention, retention (holding back) in school grades, on students' math achievement. This commentary supplements Vandecandelaere et al. (this issue) and discusses several topics in retention studies and MSM. First, we discuss the importance of equating time-varying confounders in retention studies. Second, we discuss same-grade and same-age comparisons in retention studies. Third, we discuss one important section in the authors' overview of MSM: why standard methods (e.g., ANCOVA, propensity score analysis) cannot properly adjust for time-varying confounders. Finally, using the grade retention analyses in Vandecandelaere et al. (this issue) as an example, we provide our insights on four aspects of MSM: (a) covariate selection, (b) estimation of weights, (c) evaluation of balance properties, and (d) missing data handling.     

The interaction of observational learning with overt practice: effects on motor skill learning

This study explored various methods of combining observational learning via demonstration with the effects of overt practice for learning a discrete action pattern. Three groups were compared that varied by the timing of demonstration in relation to practice. An all-pre-practice demonstration group viewed 10 pre-practice videotape demonstrations of an expert performing the skill, and then engaged in practice. An interspersed demonstration group viewed one pre-practice demonstration, then initiated practice on the skill. Every three attempts, practice was halted while participants viewed another demonstration, with this pattern repeated throughout acquisition. A combination demonstration group experienced elements of each schedule by viewing five demonstrations prior to practice, then five more once practice had begun (one every three attempts) so that modeling was completed by mid-acquisition. Ratings of form and accuracy were assessed in an acquisition phase, an immediate retention test, and a 48-h retention test. Group main effects for form scores were detected in acquisition, immediate, and 48-h retention, with the combination group obtaining the highest form scores, followed by the all-pre-practice group, and finally the interspersed group. These findings suggest that several modeling exposures before practice and several more exposures in the early stages of practice were optimal for acquisition and retention of form.     

Paradoxical intention in the treatment of urinary retention

Although most cases of psychogenic urinary retention can be ameliorated by a program composed of various behavioral techniques, there is a small percentage of cases which resists the behavioral treatment of choice. The present multiple case paper focused on the treatment of several resistant cases of functional urinary retention. Following a two week baseline period, each individual was exposed to eight weekly behavioral sessions. Whereas most cases of urinary retention have significantly improved by this time, the five individuals chosen for the present study were dissatisfied with their progress. Thus, following the eighth week, paradoxical intention was employed. Within six weeks treatment for the urinary problem was terminated as all clients were comfortable with this aspect of their daily behavior. It was hypothesized that cases of psychogenic urinary retention which resist behavioral techniques are possibly exacerbated by performance anxiety. Such anxiety can be efficiently handled by paradoxical intention.     

Personality features and mate retention strategies: Honesty–humility and the willingness to manipulate,deceive, and exploit romantic partners

Personality features are associated with several relationship outcomes. We examined whether specific personality features differed in their associations with “mate retention” strategies. We examined the unique associations that personality features had with mate retention strategies reported by 179 community members in romantic relationships for at least 6 months. Personality features were associated with each of the mate retention strategies such that positive personality features (e.g., high levels of honesty–humility) were associated with less reliance on mate retention strategies that involved manipulating, deceiving, or exploiting romantic partners. Discussion focuses on the implications of these results for understanding the connection between personality features and behaviors intended to preserve and maintain romantic relationships.     

Short-term retention of lexical-semantic representations: implications for speech production

Patients with semantic STM deficits have difficulty comprehending sentences that require the retention of several lexical-semantic representations prior to their integration into higher-level propositions (Martin, 1995: Martin & Romani. 1994). In Experiment 1, patients with a semantic retention deficit had difficulty with the same type of constructions in speech production, namely noun phrases with one or two prenominal adjectives. Their performance improved when they could produce the nouns and adjectives in sentence form, which placed smaller demands on lexical-semantic retention. In Experiment 2 these patients were better able to produce syntactically complex sentences than the prenominal adjective phrases having an equal number of content words, indicating that the findings in Experiment 1 could not be attributed to syntactic complexity. These patients produced more pauses in the sentence constructions in Experiments 1 and 2, suggesting that the timing of such productions is abnormal. In contrast, patient EA, with a phonological retention deficit, performed better than the patients with a semantic retention deficit on the AN phrases despite having a smaller STM span. She showed no significant benefit of producing sentence compared to phrase constructions, and also made fewer and shorter pauses than the other patients. These findings support the multiple capacities view of verbal working memory and suggest that the same semantic retention capacity used in language comprehension is used in speech production.     

The robustness of false memory for emotional pictures

Emotional material is commonly reported to be more accurately recognised; however, there is substantial evidence of increased false alarm rates (FAR) for emotional material and several reports of stronger influences on response bias than accuracy. This pattern is more frequently reported for words than pictures. Research on the mechanisms underlying bias differences has mostly focused on word lists under short retention intervals. This article presents four series of experiments examining recognition memory for emotional pictures while varying arousal and the control over the content of the pictures at two retention intervals, and one study measuring the relatedness of the series picture sets. Under the shorter retention interval, emotion increased false alarms and reduced accuracy. Under the longer retention interval emotion increased hit rates and FAR, resulting in reduced accuracy and/or bias. At both retention intervals, the pattern of valence effects differed based on the arousal associated with the picture sets. Emotional pictures were found to be more related than neutral pictures in each set; however, the influence of relatedness alone does not provide an adequate explanation for all emotional differences. The results demonstrate substantial emotional differences in picture recognition that vary based on valence, arousal and retention interval.     

Where did I park? A naturalistic study of spatial memory

A naturalistic study of spatial memory having temporary utility was conducted using 32 faculty and staff of a university, who park in non-reserved parking spaces, as subjects. The subjects, who were unaware of the study until interviewed, were asked to indicate on a map the exact location where they had parked their car on that day and on each of the three preceding days. Whereas retention accuracy decreased significantly across days, the recency effect was weak and overall retention proved to be very accurate. Of the subjects who varied their parking location, 88 per cent were able to indicate within three spaces where they parked on the day of the interview, and 58 per cent on the most remote day. Younger females made significantly larger retention errors across the four days than older females and younger and older males. Subjects' overall retention accuracy correlated with their overall confidence in their recollections (γ = .72). Daily ratings of ‘how busy on the job’, reported times left campus each day, parking location variability, particular parking lot used, and number of parking spaces in the distinct locations used were not significantly correlated with retention errors. In follow-up interviews, subjects reported preferring a behavioural, ‘park in a favourite spot’ strategy, with several types of imagery-based cognitive strategies being cited less frequently, and verbal encoding being the least often cited strategy.     

Basolateral amygdala lesions do not prevent memory of context-footshock training

The present studies examined the effects of basolateral amygdala (BLA) lesions induced prior to or after context-footshock training on 48-h memory, using several retention measures. In experiment 1, male Sprague-Dawley rats with bilateral BLA lesions (NMDA, 12.5 mg/mL, 0.2 μL) were given footshock training in one compartment of a two-compartment alley. Rats were habituated to the alley and 24 h later were given two footshocks in the shock compartment. Retention was tested 48 h later, using latency to enter the shock compartment and time spent freezing as measures of memory. Two days later, they were tested again and received a footshock on each re-entry of the shock compartment prior to remaining in the safe compartment for 200 consecutive seconds. The BLA lesions did not block retention as assessed by freezing or number of re-entries of the shock compartment. In experiment 2, no prior habituation was given, and only one footshock was used for the training. BLA lesions did not block retention, as indicated by latencies to enter the shock compartment on a 48-h test or by number of entries of the shock compartment. Experiment 3 examined the effects of the GABA_A agonist muscimol infused into the BLA prior to the 48-h retention test. The muscimol infusions decreased retention test entrance latencies but did not block retention as assessed by the number of subsequent entries of the shock compartment. These findings provide additional evidence that an intact BLA is not required for the acquisition or retention of context-footshock training.     

Memory improvement by glucose, fructose, and two glucose analogs: a possible effect on peripheral glucose transport

The memory-improving action of post-training, noncontingent injections of glucose was investigated in a series of experiments which examined the effects of several substances that interact with glucose metabolism on the retention of a conditioned emotional response and on blood glucose levels in male hooded rats. Although post-training glucose injections of 1, 2, and 3 g/kg all produced similar increases in blood glucose, only 2 g/kg improved retention, suggesting that attainment of a particular blood glucose level is not critical for memory improvement. Post-training injections of a range of insulin doses (0.25-4 IU/kg) failed to affect retention. Post-training injection of fructose (the same doses as were used for glucose) had no effect on blood glucose levels and, as with glucose, only the 2 g/kg dose improved retention. This finding suggests that blood glucose levels are not critical for the memory-improving effect, that glucose and fructose may act on the same substrate and, because fructose does not act directly on the brain, it raises the possibility that both substances act peripherally. Post-training injections of 2-deoxyglucose and 3-O-methylglucose both improved retention. The fact that these mostly nonmetabolized glucose analogs were effective suggests that the memory-improving action of glucose may depend on the activation of a membrane glucose transport mechanism. The implications of the possible action of glucose on peripheral transport mechanisms for understanding the effect of reinforcers on memory are discussed.     

Remembering the news: Modeling retention data from a study with 14,000 participants

A retention study is presented in which participants answered questions about news events, with a retention interval that varied within participants between 1 day and 2 years. The study involved more than 14,000 participants and around 500,000 data points. The data were analyzed separately for participants who answered questions in Dutch or in English, providing an opportunity for replication. We fitted models of varying complexity to the data in order to test several hypotheses concerning retention. Evidence for an asymptote in retention was found in only one data set, and participants with greater media exposure displayed a higher degree of learning but no difference in forgetting. Thus, forgetting was independent of initial learning. Older adults were found to have forgetting curves similar to those of younger adults.     

Calcium channel antagonists enhance retention of passive avoidance and maze learning in mice

Although a number of studies have shown that treatment with calcium channel antagonists (CCAs) can ameliorate impairments in learning and memory in aged animals, evidence for a general nootropic effect of CCAs in neurologically normal young adult animals is ambiguous. This study attempts to resolve some of this ambiguity by comparing the effects of several CCAs on retention of passive avoidance learning and acquisition and retention of appetitively motivated spatial discrimination learning in young adult mice. Animals were trained in a step through passive avoidance apparatus and, immediately after training, injected subcutaneously with different doses of nimodipine, nifedipine, amlodipine, flunarazine, diltiazem, or verapamil. Retention was tested 24 h after training. In the maze-learning task mice were treated with the same doses of the aforementioned CCAs immediately after a brief training session in a linear maze and retention was tested 24 h after training. The most effective dose of each agent in the maze-retention experiment was administered to additional groups of animals 1 h prior to training to determine the effects of CCAs on acquisition processes. The effects of central administration of CCAs were examined by intracerebroventricular injection of different doses of amlodipine immediately after passive avoidance training. Results showed (1) all peripherally administered drugs except verapamil facilitated retention of passive avoidance training in a dose-dependent manner, (2) all drugs dose dependently facilitated retention of linear maze learning, (3) all doses of the drugs (except verapamil) which facilitated maze retention also facilitated maze learning, and (4) central administration of the dihydropyridine amlodipine produced a dose-dependent facilitation of the retention of passive avoidance learning. These data indicate that drugs which block calcium channels can enhance retention of two different types of learning in mice.     

Doubts about double dissociations between short- and long-term memory

Historically, psychologists and neuroscientists have distinguished between processes supporting memory for events across retention delays of several seconds (short-term memory, STM), and those supporting memory for events across longer retention delays of minutes or more (long-term memory, LTM). Dissociations reported in some neuropsychological studies have contributed to a popular view that there must be neurally distinct memory stores that differentially support STM and LTM. In this article, we review evidence from recent studies regarding dissociations between STM and LTM. We suggest that the evidence reveals problems with claims of selective STM or LTM impairments, which in turn questions whether theories of memory need to propose neurally distinct stores for short- and long-term retention. We consider alternative ways to explain the neural mechanisms of memory across different retention intervals.     

Reducing voluntary, avoidable turnover through selection

The authors investigated the efficacy of several variables used to predict voluntary, organizationally avoidable turnover even before the employee is hired. Analyses conducted on applicant data collected in 2 separate organizations (N = 445) confirmed that biodata, clear-purpose attitudes and intentions, and disguised-purpose dispositional retention scales predicted voluntary, avoidable turnover (rs ranged from -.16 to -.22, R = .37, adjusted R = .33). Results also revealed that biodata scales and disguised-purpose retention scales added incremental validity, whereas clear-purpose retention scales did not explain significant incremental variance in turnover beyond what was explained by biodata and disguised-purpose scales. Furthermore, disparate impact (subgroup differences on race, sex, and age) was consistently small (average d = 0.12 when the majority group scored higher than the minority group).     

When we hurt the ones we love: Predicting violence against women from men's mate retention

Mate retention behaviors are designed to solve several adaptive problems such as deterring a partner's infidelity and preventing defection from the mating relationship. Although many mate retention behaviors appear to be innocuous romantic gestures (e.g., displaying resources, giving flowers), some may be harbingers of violence. We investigated the associations between male mate retention and violence against women in romantic relationships. In Study 1, 461 men reported their use of mate retention behaviors and separately completed instruments designed to assess violence in their relationships. Study 2 assessed 560 women's reports of their partners’ mate retention behaviors and the degree to which their partners used violence against them. As predicted, and across both studies, men's use of particular mate retention behaviors was related positively to female‐directed violence. Study 3 secured 2 separate data sources—husbands’ reports of their mate retention and wives’ reports of their husbands’ violence in a sample of 214 individuals forming 107 couples. The results corroborated those of Studies 1 and 2, with particular male mate retention behaviors predicting violence against romantic partners. The general discussion outlines future directions for research that are likely to result in a more comprehensive understanding of partner violence against women.