Effects of depth-of-processing and ageing on word-stem and word-fragment implicit memory tasks: Test of the lexical-processing hypothesis

The joint effects of depth-of-processing and age on repetition priming in implicit memory tests of word-fragment completion (WFC) and word-stem completion (WSC) were investigated. The experiment consisted of three study tasks (perceptual, lexical, and semantic) and four memory conditions: implicit (WSC and WFC) and explicit (WS cued recall and WF cued recall). In the WSC condition, semantic and lexical study processing produced equal priming, both superior to the perceptual study processing, whereas the WFC test showed equal priming for these three study conditions. This finding provides clear evidence, consistent with the lexical-processing hypothesis, that depth-of-processing in WSC priming reflects a lexical rather than a semantic process. It also provides support for the view that WSC and WFC involve different processes. However, there was no evidence of an age effect on either of these two implicit tasks. The data also revealed an overall significant effect of age and depth-of-processing, and an interaction between these variables on explicit cued recall tasks, indicating that older adults benefited less than younger ones from a deep encoding condition.     

Response acquisition under direct and indirect contingencies of reinforcement

We compared the effects of direct and indirect reinforcement contingencies on the performance of 6 individuals with profound developmental disabilities. Under both contingencies, completion of identical tasks (opening one of several types of containers) produced access to identical reinforcers. Under the direct contingency, the reinforcer was placed inside the container to be opened; under the indirect contingency, the therapist held the reinforcer and delivered it to the participant upon task completion. One participant immediately performed the task at 100% accuracy under both contingencies. Three participants showed either more immediate or larger improvements in performance under the direct contingency. The remaining 2 participants showed improved performance only under the direct reinforcement contingency. Data taken on the occurrence of "irrelevant" behaviors under the indirect contingency (e.g., reaching for the reinforcer instead of performing the task) provided some evidence that these behaviors may have interfered with task performance and that their occurrence was a function of differential stimulus control.     

Direct and Indirect Effects of Completion Versus Accuracy Contingencies on Practice-Exam and Actual-Exam Performance

Students in four sections of an undergraduate educational course (two large and two small sections) took out-of-class practice exams prior to actual exams for each of five course units. Each course unit consisted of five class sessions focusing on a specific developmental theme. Some sections received practice-exam credit based on the number of items completed, whereas other sections received practice-exam credit based on the number of items answered accurately. The contingencies were applied only to the practice exams. A two-way MANOVA included two independent variables (practice-exam contingency and group size) and two dependent variables (practice-exam performance and unit-exam performance). The analysis revealed a main effect for both independent variables across both dependent variables, with students performing better under the accuracy than the completion contingency and better in the small than the large groups. One exception to this overall pattern was a non-significant difference between the large and small groups on the practice exams across both contingencies.     

The effect of personality variables in the prediction of the execution of different prospective memory tasks in the laboratory

The study of prospective memory (ProM), the remembering of the delayed execution of intentions, has been growing in recent years, and we know quite a bit about the cognitive variables that affect it. But the performance of a task depends on personality variables as well as on cognitive ones, and the role of personality variables in ProM has only been partially studied, the results being less conclusive. We sought to address two main objectives: (1) to quantify the joint influence of cognitive and personality variables on three ProM tasks in the laboratory (two based on events and the other on time), and (2) to identify the personality profiles of those who perform well in these three ProM tasks as opposed to those who do not. The cognitive and personality variables were evaluated with two sessions of 157 participants. The 16 PF-5 was applied (Cattell, Cattell & Cattell, 1993) and other cognitive variables were measured. With the data obtained, we ran several regression analyses to determine how some cognitive variables (sustained attention, verbal fluency, interference, retrospective memory, selective attention) and personality factors (tested using the 16 PF-5) can help to explain the variance in the performance of prospective memory tasks. Our results show that the contribution of personality predictor variables is moderate and smaller than that of the cognitive variables for predicting the execution of ProM tasks in the laboratory. Furthermore the intervention of the personality variables differs depending on the ProM tasks used. Global self-control and rule-consciousness were the personality variables that contributed the most in the prediction of the scores in the ProM tasks that were used.     

The relation between phonological awareness and working memory

Previous research has failed to show a relation between children's working memory and performance on the phonological sound categorization task (M. J. Snowling, C. Hulme, A. Smith, & J. Thomas, 1994). However, the test used to assess working memory in that experiment was more comparable to a short-term memory task, which assesses storage capacity, than to a working memory task, which has both storage and processing components. In the present study, we compared the predictive power of both types of memory tasks on 2 measures of phonological awareness, the sound categorization task and a phoneme deletion task, in 7- and 8-year-olds (mean age = 8 years 1 month). The children's reading ability was also assessed. Fixed-order multiple-regression analyses showed that the sound categorization task has a higher working memory demand than the phoneme deletion task: Working memory predicted independent variance in performance only on the sound categorization task. The short-term memory task did not account for significant independent variance in performance on either of the measures of phonological awareness.     

Metacognition and part-set cuing: Can interference be predicted at retrieval?

Although prior research has examined predictions of memory performance under conditions of interference at encoding, predictions of memory performance have not been examined for interference introduced via cues at retrieval. This was investigated in the present study by exposing participants to a random subset of to-be-recalled items just prior to retrieval (part-set cuing) and then eliciting an overall prediction of memory performance. Across three experiments, participants in part-set cuing conditions recalled proportionally fewer items than did participants who were not exposed to any cues. However, participants were unable to predict the detrimental effect of part-set cues on memory performance in either a semantic (Experiment 1) or an episodic (Experiment 2) memory task. Predictions were better calibrated after practice with part-set cuing, and there was evidence that prior experience with part-set cuing transferred to predictions made for a different part-set cuing task (Experiment 3). This suggests that only under some conditions are participants sensitive to the diminished accessibility of memories wrought by part-set cues and illustrates situations in which participants are or are not aware of variables at retrieval that influence memory performance.     

Priming and aging: further evidence of preserved memory function

Priming effects in word-stem completion were compared with cued recall in young and older adults. Cued recall showed large effects of age and also of levels of processing, but these variables had little influence on priming in word-stem completion. Free recall showed large effects of age as well as superior recall for words that had been generated rather than read at study, but priming in word-stem completion was little influenced by age, and it was greater for words that had been read at study rather than generated. These findings were interpreted as providing further evidence that age-related impairments in memory performance are greatly reduced in implicit compared with explicit tests. They also provide convergent evidence for classifying word-stem completion as a data-driven rather than conceptually driven task.     

Effects of attentional load and ageing on word-stem and word-fragment implicit memory tasks

The joint effects of reduced attention and age on repetition priming in implicit memory tests of word-fragment completion (WFC) and word-stem completion (WSC) were investigated. An attention load during the study phase reduced the extent of repetition priming in the WSC condition but not in WFC. This finding provides support for the view that WSC and WFC involve different processes. However, there was no evidence of an age effect on either of these two types of implicit tasks. The data also revealed an overall significant effect of age and reduced attention on explicit cued recall tasks.     

进行中任务变化对轻度认知功能障碍者基于事件前瞻记忆的影响

本实验采用2被试组别(MCI组、正常老年组) × 3进行中任务变化(无变化、顺序变化、随机变化)被试间设计探究进行中任务变化对轻度认知功能障碍者基于事件前瞻记忆的影响。结果表明：(1)轻度认知功能障碍者的前瞻记忆成绩显著低于正常老年人的前瞻记忆成绩; (2)进行中任务变化对两组被试前瞻记忆和进行中任务的反应时影响存在显著差异。进行中任务变化越大, 轻度认知功能障碍者完成前瞻记忆和进行中任务的反应速度越慢; 而正常老年被试则不受影响。研究支持前瞻记忆策略加工的理论观点, 认为执行功能损伤可能是导致轻度认知功能障碍者前瞻记忆失败的主要原因。     

The interaction of word frequency and concreteness in immediate serial recall

Word frequency and word concreteness are language attributes that have been shown to independently influence the recall of items in verbal short-term memory (STM). It has been argued that such effects are evidence for the action of long-term memory knowledge on STM traces. However, research to date has not investigated whether these variables interact in serial recall. In two experiments, we examined the behavior of these variables under factorial manipulation and demonstrated that the effect of word frequency is dependent on the level of concreteness of items. Serial recall performance is examined with reference to two explanatory approaches: Walker and Hulme’s (1999) dual-redintegration account and language-based models of STM. The data indicate that language-based models are more compatible with the observed effects and challenge the view that frequency and concreteness effects in STM are the products of distinct mechanisms.     

Mood and prospective memory

This study considered the relationship between mood states, prospective memory, and retrospective memory among a non-clinical sample of undergraduate students. Multiple regression analyses with simultaneous entry of variables were undertaken to examine the unique contributions of the alternate memory test and the emotional states to memory test performance. As expected, retrospective free recall performance and anxiety made unique and significant contributions to performance on the prospective memory task. However, only prospective memory performance emerged as a significant predictor of retrospective free recall. It is suggested that none of the mood measures emerged as a significant predictor of retrospective memory performance because they do not account for unique variance. In contrast, the relationship between anxiety and prospective memory appears to be due to factors uniquely associated with anxiety, and unrelated to depression.     

Mood and Prospective Memory

This study considered the relationship between mood states, prospective memory, and retrospective memory among a non-clinical sample of undergraduate students. Multiple regression analyses with simultaneous entry of variables were undertaken to examine the unique contributions of the alternate memory test and the emotional states to memory test performance. As expected, retrospective free recall performance and anxiety made unique and significant contributions to performance on the prospective memory task. However, only prospective memory performance emerged as a significant predictor of retrospective free recall. It is suggested that none of the mood measures emerged as a significant predictor of retrospective memory performance because they do not account for unique variance. In contrast, the relationship between anxiety and prospective memory appears to be due to factors uniquely associated with anxiety, and unrelated to depression.     

The effects of hippocampal lesions on learning, memory, and reward expectancies

The hippocampus appears to be critical for the formation of certain types of memories. Hippocampal-lesioned animals fail to exhibit some spatial, contextual, and relational associations. After aspiration lesions of the hippocampus and/or cortex, male rats were allowed to recover for three weeks before being trained on a matching-to-position task. The matching-to-position task was altered to influence the type of cognitive strategies a subject would use to solve the task. The main behavioral manipulation was the reinforcement contingency assignment: Use of a differential outcomes procedure (DOP) or a nondifferential outcomes procedure (NOP). The DOP involves correlating each to-be-remembered event with a distinct reward condition via Pavlovian trace conditioning, whereas the NOP results in random reward contingency. We found that hippocampal lesions did retard learning the matching rule, regardless of the reinforcement contingency assignment. However, when delay intervals were added to the task memory performance of subjects with hippocampal lesions was dramatically impaired--if subjects were not trained with the DOP. When subjects were trained with the DOP, the hippocampal lesion had a marginal effect on delayed memory performance. These findings demonstrate two important points regarding lesions of the hippocampus: (1) hippocampal lesions have a minimal effect on the on the ability of rats to use reward information to solve a delayed discrimination task; (2) rats with hippocampal lesions have the ability to learn about reward information using Pavlovian trace conditioning procedures.     

A method for judging measures of stochastic dependence: further comments on the current controversy.

A large number of reports have been published on stochastic independence between implicit and explicit measures of memory. This is often taken to imply that different memory systems mediate implicit and explicit memory performance. In these cases, stochastic independence is inferred from contingency analysis of overall success rates in two memory tasks when performance in one or both of the tasks is, to a large extent, mediated by factors other than memory. Typically, the difference between performance with studied and nonstudied items is not large in implicit memory tasks. It is argued that this must be taken into account when evaluating the contingency analysis. A method is presented for estimating the relevant joint and conditional probabilities, assuming that the aspects of performance in the two tasks that are related to memory are dependent to the maximum possible extent. The method is applied to a number of published studies, and it is shown that the difference between these estimated probabilities and those given by stochastic independence is too small to allow any conclusion to be drawn about memory systems from contingency analysis of data reported in these studies.     

Does survival processing enhance implicit memory?

Recent research has shown that human memory may have evolved to remember information that has been processed for the purpose of survival, more so than information that has been processed for other purposes, such as home-moving. We investigated this survival-processing advantage using both explicit and implicit memory tests. In Experiment 1, participants rated words in one of three scenarios: survival, pleasantness, and moving, followed by a timed stem-cued recall/stem-cued completion task. Items were completed more quickly in the survival scenario, as compared with the other two for the explicit task, but no differences were found across conditions in the implicit task. In Experiment 2, the implicit task was changed to concreteness judgments to encourage more conceptual processing. Again, the survival-processing advantage occurred in the explicit task (speeded item recognition), but not in the implicit task. These results suggest that a survival-processing advantage may benefit participants’ memory performance only during explicit retrieval.     

Implicit memory and depression: An analysis of perceptual and conceptual processes

A small number of studies have reported impaired explicit memory and intact implicit memory performance in participants classified as depressed. In the present study we examined this finding taking account of the distinction between datadriven and conceptually driven processing. The performance of participants diagnosed with depression was examined on implicit and explicit memory tasks which were designed to tap either predominantly perceptual or conceptual processes. Depressed participants demonstrated performance deficits on both the implicit and explicit conceptual tasks (category association and free recall, respectively) but showed intact performance in the implicit perceptual task (word-fragment completion). These results suggest that people with severe depression show deficits in conceptual processing and that this deficit occurs under both explicit and implicit task instructions.     

Differential effects of personality on access to various long-term memory codes

Arousal, as indexed by personality measures, has been related to memory encoding, organization, and retrieval. In an attempt to investigate one of the component information-processing mechanisms underlying both encoding and retrieval, the effects of introversion-extraversion on performance in a simultaneous matching task was investigated. As predicted from earlier research, personality did not influence performance on a physical identity matching task but extraverts were faster than introverts in making taxonomic category matches (a semantic task). Somewhat unexpectedly, extraverts were also faster at making “homophone” identity matches. Arousal, then, appears to influence access to long-term memory codes of any type—a characteristic that may be reflected in tests of both encoding and retrieval.     

Dissociating word stem completion and cued recall as a function of divided attention at retrieval

The aim of this study was to investigate the widely held, but largely untested, view that implicit memory (repetition priming) reflects an automatic form of retrieval. Specifically, in Experiment 1 we explored whether a secondary task (syllable monitoring), performed during retrieval, would disrupt performance on explicit (cued recall) and implicit (stem completion) memory tasks equally. Surprisingly, despite substantial memory and secondary costs to cued recall when performed with a syllable-monitoring task, the same manipulation had no effect on stem completion priming or on secondary task performance. In Experiment 2 we demonstrated that even when using a particularly demanding version of the stem completion task that incurred secondary task costs, the corresponding disruption to implicit memory performance was minimal. Collectively, the results are consistent with the view that implicit memory retrieval requires little or no processing capacity and is not seemingly susceptible to the effects of dividing attention at retrieval.     

Do cleaner fish learn to feed against their preference in a reverse reward contingency task?

The ability to control impulsive behaviour has been studied in animals with a standard test in which subjects need to choose the smaller of two food items in order to receive the larger one (reverse reward contingency). As a variety of mammals that have been tested so far (mostly primates) have great difficulties to solve the task, it has been proposed that it is generally cognitively demanding. However, according to an ecological approach to cognition, a species’ ability to solve the task should not depend on its general cognitive abilities but on whether its ecology causes selective pressure on the ability to restrain foraging behaviour. We tested this hypothesis using the cleaner wrasse (Labroides dimidiatus), a fish species that feeds against its preference in nature when engaging in cleaning interactions with so called ‘client fish’. None of the eight tested individuals learned to choose a non-preferred item after 200 trials. In a subsequent test, one subject learned to respond correctly in a large or none contingency task (only the choice of the small food was rewarded). After a short re-experience treatment, this individual learned to solve the reverse reward task after 30 trials. In conclusion, we did not find support for the general idea that interactions with clients prepared cleaners to quickly solve a reverse reward test. However, the results suggest that the potential to solve a reverse reward contingency may not be restricted to mammals but could be present also in a fish species in which the problem of choosing a non-preferred food over a preferred one is an ever present challenge in nature.     

Aging affects word-stem completion and recognition but not category generation

In this study, we investigated the effect of aging on two implicit memory tasks, word-stem completion and category generation, and on explicit recognition. We compared the performance of young and older adults on these implicit memory tasks with those of explicit recognition. We expected better performance of young than older adults in the explicit memory task and similar priming in both implicit memory tasks. The results showed that young adults performed better than older adults in the recognition task. Moreover, both age groups showed priming in the implicit memory tasks, although priming was greater in young adults compared to older adults in the word-stem completion memory task, whereas both age groups showed similar levels of priming in the category generation task. The present results showed dissociations as a function of age not only between the explicit and the implicit tasks but also between the implicit tasks.