How similar is false recognition to veridical recognition objectively and subjectively?

Three recognition memory experiments were conducted using modified Deese-Roediger-McDermott (DRM) and DRM paradigms. In Experiment 1, the reaction time (RT) of the false alarms to critical nonpresented words (false memory) was compared with the RT of hits to the critical presented words and with the RT of hits to the studied list words (true memory). The RT of the false alarms to the critical nonpresented words was significantly longer than that of the hits to the critical words and than that of the studied list words. In Experiment 2, in addition to RT, participants' confidence level was measured on a 4-point scale for a yes or no response. Confidence rating was significantly higher for the hits to the critical presented words and to the list words than for the false alarms to the critical non-presented words. Experiment 3 further showed that how similar false memory experience was to that of true memory was a function of retention size (number of lists of words retained in memory). In all three experiments, the participants' recognition RTs distinguished false memory from veridical memory, and in Experiments 2 and 3, so did their confidence ratings. Therefore, false memory and veridical memory differ at both the objective and the subjective levels. The results are consistent with a single familiarity dimension model of recognition memory.     

Effectiveness of follow‐up reminiscence therapy on autobiographical memory in pathological ageing

The objective is to examine the effects of reminiscence therapy (RT) on total, episodic and semantic autobiographical memory in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) groups, testing the effects of RT on different stages of autobiographical memory, and its effectiveness at follow‐up. A sample composed of 43 aMCI (27 treatments, 16 controls) and 30 AD (15 treatments, 15 controls) subjects were evaluated with the Autobiographical Memory Interview (AMI) test. The RT consisted of 10 sessions lasting 60 minutes each. Both groups, aMCI and AD, showed significant effects on overall autobiographical memory; aMCI showed significant main effects on episodic and semantic autobiographical memory in the treatment group, increasing scores in both cases. For AD, significant effects were observed on autobiographical episodic memory, showing an increase in the treatment group from Time 1 to follow‐up; semantic memory showed a decrease in the control group from Time 1 to follow‐up. Results show that RT implementation and follow‐up are effective in increasing autobiographical memory in subjects with aMCI and AD.     

Flexibility in scanning described images

Two experiments investigated why past research has shown that described images lead to the typical increase in reaction time (RT) with increasing memory set size (m), but undescribed images do not. Experiment 1 used ms 6 through 8. A described image group showed a linear relation between m and RT up to a m of 6, and no increase in RT thereafter. A story group (which was asked to tell a brief story for words in a memory set) and a repetition group showed a linear relation between m and RT throughout the range of ms, whereas an image group showed no relation between m and RT. Experiment 2 essentially replicated the first experiment but manipulated memory strategy as a within subject variable. Similar results were found. The apparent change from "serial" to "parallel" processing by the described image groups in both studies reinforces the notion of flexibility in processing, particularly when multiple representations are formed or when multiple encoding strategies are used.     

知觉或记忆条件下对连续变化刺激的相似判断

控制不同材料(图形和字母)的大小、位置和长宽比连续变化,在标准和待判断刺激同时(知觉任务)或相继呈现(记忆任务)两种条件下进行相似判断的实验研究。结论为(1)任务方式对图形的相似判断有非常显著的影响;(2)知觉任务中相似判断的反应时非常显著地长于记忆任务中的反应时;(3)对材料各种特征的相似判断和加工速度差异非常显著．某些特征在相似表征中有较重要的作用。     

The effect of memory load on reaction time in character classification

In order to investigate the effect of memory load on reaction time (RT), choice RT trials were embedded in a binary character classification task using the varied set procedure. Twelve Ss performed in experimental blocks, as well as in control blocks consisting of character classification trials only. In experimental blocks, every trial began as a classification trial with the presentation of a new positive set. On a random half of these trials, however, a choice RT stimulus was presented instead of a probe letter and S simply made the indicated response. Results indicated that memory load had no effect on the choice RT trials. Embedding choice RT trials in the classification task affected the intercept (but not the slope) of the function relating classification RT to memory load. This result implies that the increase in latency usually obtained in classification experiments is entirely due to an increase in the duration of the memory searching stage of processing.     

Response-time evidence for mixed memory states in a sequential-presentation change-detection task

Response-time (RT) and choice-probability data were obtained in a rapid visual sequential-presentation change-detection task in which memory set size, study-test lag, and objective change probabilities were manipulated. False “change” judgments increased dramatically with increasing lag, consistent with the idea that study items with long lags were ejected from a discrete-slots buffer. Error RTs were nearly invariant with set size and lag, consistent with the idea that the errors were produced by a stimulus-independent guessing process. The patterns of error and RT data could not be explained in terms of encoding limitations, but were consistent with the hypothesis that long retention lags produced a zero-stimulus-information state that required guessing. Formal modeling of the change-detection RT and error data pointed toward a hybrid model of visual working memory. The hybrid model assumed mixed states involving a combination of memory and guessing, but with higher memory resolution for items with shorter retention lags. The work raises new questions concerning the nature of the memory representations that are produced across the closely related tasks of change detection and visual memory search.     

Individual differences in secondary task performance

The purpose of this research was to use secondary task performance as a predictor of performance on a difficult primary task. Reaction time (RT) to secondary probes that occurred during the rehearsal period of an easy memory task were used to measure spare capacity associated with the memory task. This measure was then correlated with performance on a harder version of the same memory task. Experiments 1-4 involved a paired associate memory task. Probe RT was sensitive to the difficulty of the paired associate task, and analysis of individual differences showed that probe RT during the easy version of the task was correlated with performance on a harder version of the task. Experiment 4 also utilized a spatial memory task. Probe RT was less sensitive to the demands of the spatial memory task, and in that case, the "easy-to-hard" prediction was not successful.     

Effects of divided attention in the word-fragment completion task with unique and multiple solutions

A study with 114 young adults investigated the correlations of intelligence factors and working-memory capacity with reaction time (RT) tasks. Within two sets of four-choice RT tasks, stimulus–response compatibility was varied over three levels: compatible, incompatible, and arbitrary mappings. Two satisfactory measurement models for the RTs could be established: A general factor model without constraints on the loadings and a nested model with two correlated factors, distinguishing compatible from arbitrary mappings, with constraints on the loadings. Structural models additionally including factors for working memory and intelligence showed that the nested model with correlated factors is superior in fit. Working-memory capacity and fluid intelligence were correlated strongly with the nested factor for the RT tasks with arbitrary mappings, and less with the general RT factor. The results support the hypothesis that working memory is needed to maintain arbitrary bindings between stimulus representations and response representations, and this could explain the correlation of working-memory capacity with speed in choice RT tasks.     

Task-switching cost and repetition priming: Two overlooked confounds in the fixed-set procedure of the Sternberg paradigm and how they affect memory set-size effects

Subjects performed Sternberg-type memory recognition tasks (Sternberg paradigm) in four experiments. Category-instance names were used as learning and testing materials. Sternberg's original experiments demonstrated a linear relation between reaction time (RT) and memory-set size (MSS). A few later studies found no relation, and other studies found a nonlinear relation (logarithmic) between the two variables. These deviations were used as evidence undermining Sternberg's serial scan theory. This study identified two confounding variables in the fixed-set procedure of the paradigm (where multiple probes are presented at test for a learned memory set) that could generate a MSS RT function that was either flat or logarithmic rather than linearly increasing. These two confounding variables were task-switching cost and repetition priming. The former factor worked against smaller memory sets and in favour of larger sets whereas the latter factor worked in the opposite way. Results demonstrated that a null or a logarithmic RT-to-MSS relation could be the artefact of the combined effects of these two variables. The Sternberg paradigm has been used widely in memory research, and a thorough understanding of the subtle methodological pitfalls is crucial. It is suggested that a varied-set procedure (where only one probe is presented at test for a learned memory set) is a more contamination-free procedure for measuring the MSS effects, and that if a fixed-set procedure is used, it is worthwhile examining the RT function of the very first trials across the MSSs, which are presumably relatively free of contamination by the subsequent trials.     

Memory scanning of described images and undescribed images: Hemispheric differences

Seamon (1972) has found that reaction times (RTs) to memory probes do not increase with memory set size (M) for words encoded in mental images in a memory scanning task. Rothstein and Atkinson (1975) have failed to replicate Seamon’s results. Experiment 1 investigated this discrepancy by manipulating one methodological difference (whether images were or were not described) between the two investigations. Results revealed that described images produced typical linear increases in RT with M. Undescribed images, however, revealed no change in RT with M for positive probes (i.e., the word presented was contained in the current memory set). Experiment 2 manipulated to which visual field probes were presented (RVF — right visual field; LVF = left visual field). Results showed that the imagery group showed no relation between RT and M for probes presented to the LVF, but a linear relation for probes presentedto the RVF. Described-image and repetition groups revealed a linear relation between RT and M no matter which visual field received the probe.     

Evaluating the unequal-variance and dual-process explanations of zROC slopes with response time data and the diffusion model

We tested two explanations for why the slope of the z-transformed receiver operating characteristic (zROC) is less than 1 in recognition memory: the unequal-variance account (target evidence is more variable than lure evidence) and the dual-process account (responding reflects both a continuous familiarity process and a threshold recollection process). These accounts are typically implemented in signal detection models that do not make predictions for response time (RT) data. We tested them using RT data and the diffusion model. Participants completed multiple study/test blocks of an "old"/"new" recognition task with the proportion of targets and the test varying from block to block (.21, .32, .50, .68, or .79 targets). The same participants completed sessions with both speed-emphasis and accuracy-emphasis instructions. zROC slopes were below one for both speed and accuracy sessions, and they were slightly lower for speed. The extremely fast pace of the speed sessions (mean RT=526) should have severely limited the role of the slower recollection process relative to the fast familiarity process. Thus, the slope results are not consistent with the idea that recollection is responsible for slopes below 1. The diffusion model was able to match the empirical zROC slopes and RT distributions when between-trial variability in memory evidence was greater for targets than for lures, but missed the zROC slopes when target and lure variability were constrained to be equal. Therefore, unequal variability in continuous evidence is supported by RT modeling in addition to signal detection modeling. Finally, we found that a two-choice version of the RTCON model could not accommodate the RT distributions as successfully as the diffusion model.     

Effect of memory set-size upon event related potentials for concrete and abstract kanji stimuli.

Event related potentials (ERP) and reaction times (RT) were recorded during the performance of memory-retrieval tasks using the Japanese kanji characters. P300 latency and RT increased as the memory set-size increased. The slope differences between RT and P300 latency were larger for stimuli when concrete kanji were used than when abstract kanji were used. This suggests that, in memory search, the 20 subjects were likely to employ direct lexical access when processing concrete kanji and likely to use phonetic coding when processing abstract kanji.     

Disruptions of preparatory attention contribute to failures of prospective memory

In two experiments, we examine the efficacy of preparatory attentional processes and intention superiority as explanations of the finding that response time (RT) for prospective memory (PM) cue misses is often faster than that for ongoing activity trials or PM cue hits. RT was faster for prospective misses than for ongoing activity trials, demonstrating an intention superiority effect. RT was also faster for ongoing activity trials preceding prospective misses than for those preceding prospective hits. We interpret this finding as reflecting variation in the efficiency of preparatory attentional processes during task performance, leading to failures of PM when preparatory attentional processes are suboptimal.     

The effect of directed forgetting on the time to remember

A recognition memory task was used to determine whether the search set is reduced by cueing subject to forget a part of the input. Correct recognition reaction time was used to infer the size of the search set. The principal results were that RT on forget trials was faster than RT on remember trials and that RT was fastest when the forget cue was presented at the outset of the trial rather than after the material had been presented. These findings are generally consistent with the hypothesis that selective search is responsible for the enhancement of recall produced by forget instructions in earlier studies.     

Searching short-term memory for linear-positioning movements

To determine whether memory search for movements was serial or parallel, the search processes involved in a short-term motor-memory paradigm were investigated. A linear-positioning task was used to present a series of 1, 2, or 3 movements in a memory set. Upon completion of a memory set, subjects were presented with a search movement. The search movement was either the same length as one of the memory-set movements ("yes" response) or a different length ("no" response). Four subjects completed three consecutive days of testing. On Day 1 RT and movement length were practiced. On Day 2 the subjects were required to search a memory set of movements and respond in the yes condition by lifting the index finger of the left hand. This movement terminated a RT search clock. The same procedures were followed on Day 3, except that a no response was indicated by lifting the index finger. A 2 X 3 X 3 (response X memory set X RT trials) within-subjects analysis yielded nonsignificant main effects and interactions. The results were discussed in relation to verbal memory.     

Working memory and attention in pediatric brain tumor patients treated with and without radiation therapy

Children are at risk for cognitive difficulties following the diagnosis and treatment of a brain tumor. Longitudinal studies have consistently demonstrated declines on measures of intellectual functioning, and recently it has been proposed that specific neurocognitive processes underlie these changes, including working memory, processing speed, and attention. However, a fine-grained examination of the affected neurocognitive processes is required to inform intervention efforts. Radiation therapy (RT) impacts white matter integrity, likely affecting those cognitive processes supported by distributed neural networks. This study examined working memory and attention in children during the early delayed stages of recovery following surgical resection and RT. The participants included 27 children diagnosed with pediatric brain tumor, treated with (n = 12) or without (n = 15) RT, who completed experimental and standardized measures of working memory and attention (n-back and digit span tasks). Children treated with radiation performed less well than those who did not receive radiation on the n-back measure, though performance at the 0-back level was considerably poorer than would be expected for both groups, perhaps suggesting difficulties with more basic processes such as vigilance. Along these lines, marginal differences were noted on digit span forward. The findings are discussed with respect to models of attention and working memory, and the interplay between the two.     

The effect of an extraneous added memory set on item recognition: A test of parallel-dependent vs. serial-comparison models

The linear increase in response time (RT) in item recognition as a function of memory set size may be attributed either to increased memory search, as in Sternberg’s serial-comparison model, or to increased interference and competition for a limited processing capacity, as in a parallel-dependent model. An additional memory load was imposed on the normal item recognition task. If the normal task involved letters, the additional task involved digits, or vice versa. The added set was presented before and tested after the normal core set was presented and tested. Across the four trial blocks, the subjects did come to dissociate the two memory sets, but this could be due as much to directed rehearsal as to directed search when other results, including the subjects’ postsession reports, are considered. Other findings, such as the higher error rate and shorter RT for positive than negative trials, seem to reflect differences in effective trace strength, and thus are consistent with the parallel-dependent model.     

The role of generation in recognition

In contrast to the widely accepted opinion, a negatively accelerated RT function was obtained with varied mapping of stimuli to responses in Sternberg's (1966) recognition task when the task was designed to reduce proactive inhibition. These results are similar to the results obtained in the distractor task. Those aspects of the distractor task that proactively inhibit recall of the trigram are also necessary to produce a linear RT function in the recognition task. Hence, the varied-set procedure only results in a linear RT function when the memory sets on successive trials contain similar items, but not when successive trials contain different kinds of items, e.g., digits versus letters. Also, once subjects have been trained on the fixed-set procedure to produce a negatively accelerated RT function, the training transfers completely and immediately to entirely new sets of targets and distractors. The results of both tasks, as well as other retrieval tasks, can be explained by a model containing a single comparison process and an optional serial generation process which is invoked to increase the discriminability of the memory set from distractors.     

Choice reaction times in children: Error and post-error responses,and the repetition effect

Analysis of the frequency and nature of error and post-error responses in the serial choice reaction times (RTs) of children between 5 and 12 years essentially replicate findings in adults. Errors are few and fast, tend to be made on fingers closely related to the correct responding finger, and are followed by a marked slowing in response rate. This pattern of results is interpreted in terms of a strategy to optimize performance with respect to instructions emphasizing both speed and accuracy. Importantly, this may be seen to reflect the activity, even in the youngest of children, of a finely-tuned feedback mechanism for error detection. Only the extent of immediate post-error slowing shows a decline with age, and is referred to improvements in response programming. Repetition RT is much faster than alternation RT (the “Repetition Effect”) and improves much less rapidly with age. Reduction of the Repetition Effect with age is consistent with theories of RT in which signals are categorized by retrospective search in short-term memory. The girls' advantage in gross RT is found to be confined to alternation RT only. The particular contribution of alternation RT both to the development of, and sex difference in, gross RT is related to the greater response organization involved in rapidly switching between fingers and hands.     

Successful detection of verbal and visual concealed knowledge using an RT‐based paradigm

An increasing number of researchers are exploring variations of the Concealed Knowledge Test (CKT) as alternatives to traditional ‘lie‐detector’ tests. For example, the response times (RT)‐based CKT has been previously shown to accurately detect participants who possess privileged knowledge. Although several studies have reported successful RT‐based tests, they have focused on verbal stimuli despite the prevalence of photographic evidence in forensic investigations. Related studies comparing pictures and phrases have yielded inconsistent results. The present work compared an RT‐CKT using verbal phrases as stimuli to one using pictures of faces. This led to equally accurate and efficient tests using either stimulus type. Results also suggest that previous inconsistent findings may be attributable to study procedures that led to better memory for verbal than visual items. When memory for verbal phrases and pictures were equated, we found nearly identical detection accuracies. Copyright © 2007 John Wiley & Sons, Ltd.