Serial-position effects for lures in short-term recognition memory

Serial-position curves for targets in short-term recognition memory show modest primacy and marked recency. To construct serial-position curves for lures, we tested orthographic neighbours of study words and assigned each lure to the position of its studied neighbour. The curve for lures was parallel to that for targets. In Experiment 2, only half the lures were neighbours of study words; the other half overlapped a study word by a single letter. The serial-position curve for neighbours of study items was now flatter than the curve for targets. The results are inconsistent with theories in which any factor that benefits targets must hinder lures. Instead, they demand a decision mechanism that assigns a role to item-specific information, as well as to general familiarity information, such as dual-process theory.     

Environmental context-dependent recognition memory using a short-term memory task for input

Although many studies have demonstrated that recall is better when tested in the learning environmental context (EC) than in a new EC, almost all of the studies have failed to find EC-dependent memory when recognition was used to measure memory. Evidence of EC-dependent recognition, however, was found in the three experiments of the present study, in which an incidental short-term memory task was used for input of learned material. The results suggest that type of processing during input is a predictor of context-dependent recognition; material studied for a long-term memory test is not susceptible to background context effects, whereas material merely maintained for a short-term memory test is more apt to lead to EC-dependent recognition.     

Reproduction and recognition in short-term visual memory

Reproduction and recognition in short-term visual memory was tested. In Experiment I, it was confirmed that the ability to reproduce visual figures in STM correlated with the ability to describe them. No such correlation was obtained when recall was by recognition. In Experiments II and III the mechanisms involved in the two types of recall were investigated by varying the character of the task interpolated in the retention interval. Results support the view that reproduction has a verbal component which is lacking in recognition.     

Tests of an exemplar model for relating perceptual classification and recognition memory

Experiments were conducted in which Ss made classification, recognition, and similarity judgments for 34 schematic faces. A multidimensional scaling (MDS) solution for the faces was derived on the basis of the similarity judgments. This MDS solution was then used in conjunction with an exemplar-similarity model to accurately predict Ss' classification and recognition judgments. Evidence was provided that Ss allocated attention to the psychological dimensions differentially for classification and recognition. The distribution of attention came close to the ideal-observer distribution for classification, and some tendencies in that direction were observed for recognition. Evidence was also provided for interactive effects of individual exemplar frequencies and similarities on classification and recognition, in accord with the predictions of the exemplar model. Unexpectedly, however, the frequency effects appeared to be larger for classification than for recognition.     

The effect of feature frequency on short-term recognition memory

We report two experiments using Sternberg's (1969) multitrial recognition-memory paradigm. We used colored shapes as stimuli and manipulated the frequency of the shapes (but not of the colors) across trials. For lures containing an extralist shape (i.e., a shape not studied in the current study list), responses were faster if the shape had occurred infrequently than if it had occurred frequently in the preceding trials. For lures containing an extralist color and a studied shape, by contrast, the frequency of the shape in the preceding trials was irrelevant. We conclude that correct rejections depend solely on contradictory evidence. Furthermore, low-frequency target items were recognized more easily than high-frequency targets. Both the interaction of frequency with the features of the lures and the main effect of frequency for the targets are problematic for current accounts of recognition.     

Effects of sleep deprivation on short-term recognition memory.

A probe-recognition short-term memory paradigm was used to inquire into the precise effects of sleep deprivation on human memory. It was found that recognition performance, as measured by d', was generally impaired for each subjects after 24 hr of sleep deprivation. While d' was shown to decrease exponentially as the number of items intervening between the target and the probe increased, this decay rate was not affected by sleep loss. In addition there was confirmation of a previously observed increase in the positive skewness of reaction times after wakefulness. The data were consistent with the hypothesis that sleep deprivation increases the occurrence of lapses, periods of lowered reactive capacity, which prevent the encoding of items in short-term memory.     

Homogeneity computation: How interitem similarity in visual short-term memory alters recognition

Visual short-term recognition memory for multiple stimuli is strongly influenced by the study items’ similarity to one another—that is, by their homogeneity. However, the mechanism responsible for this homogeneity effect has remained unclear. We evaluated competing explanations of this effect, using controlled sets of Gabor patches as study items and probe stimuli. Our results, based on recognition memory for spatial frequency, rule out the possibility that the homogeneity effect arises because similar study items are encoded and/or maintained with higher fidelity in memory than dissimilar study items are. Instead, our results support the hypothesis that the homogeneity effect reflects trial-by-trial comparisons of study items, which generate a homogeneity signal. This homogeneity signal modulates recognition performance through an adjustment of the subject’s decision criterion. Additionally, it seems the homogeneity signal is computed prior to the presentation of the probe stimulus, by evaluating the familiarity of each new stimulus with respect to the items already in memory. This suggests that recognition-like processes operate not only on the probe stimulus, but on study items as well.     

The extralist-feature effect: evidence against item matching in short-term recognition memory

The authors varied the similarity between negative probes and study items in a short-term item-recognition task. Current models treat similarity as a function of the number of occurrences of the probe's features in the study set, a factor that is often confounded with the number of the probe's features occurring in the study set. Unconfounded comparisons showed that performance reflected only the latter factor, with response time a linear function of the number of probe features in the study set. The effect was obtained for both stimuli with manipulated features (colored shapes) and words. Number of presented features is a global property of the study list, but existing global models calculate familiarity by averaging across item matches and cannot readily accommodate the data. The authors proposed that the probe's features are compared with a global representation of the study set's features.     

A new model of verbal short-term memory

Two experiments tested a neo-Piagetian model of verbal short-term memory and compared it with the articulatory loop model. Experiment 1 (n = 113, age range 9-11) tested word span for 2-, 3-, and 4-syllable words, with both visual and auditory presentation. Experiment 2 (with the same participants) tested recall of visually presented supraspan lists. Measures of M capacity (as conceived in Pascual-Leone's neo-Piagetian theory) and articulation rate were also used. The proposed model can account for the effects of M capacity, word length, and presentation modality. The fit of this model to the data was acceptable, and parameter estimates were consistent across experiments. Furthermore, a correlation was found between M capacity and word span which resisted partialling out of age and articulation rate.     

A feature-segmentation model of short-term visual memory

A feature-segmentation model of short-term visual memory (STVM) for contours is proposed. Memory of the First stimulus is maintained until the second stimulus is observed. Three processes interact to determine the relationship between stimulus and response: feature encoding, memory, and decision. Basic assumptions of the model are twofold: (i) the STVM system divides a contour into convex parts at regions of concavity; and (ii) the value of each convex part represented in STVM is an independent Gaussian random variable. Simulation showed that the five-parameter fits give a good account of the effects of the four experimental variables. The model provides evidence that: (i) contours are successfully encoded within 0.5 s exposure, regardless of pattern complexity; (ii) memory noise increases as a linear function of retention interval; (iii) the capacity of STVM, defined by pattern complexity (the degree that a pattern can be handled for several seconds with little loss), is about 4 convex parts; and (iv) the confusability contributing to the decision process is a primary factor in deteriorating recognition of complex figures. It is concluded that visually presented patterns can be retained in STVM with considerable precision for prolonged periods of time, though some loss of precision is inevitable.     

Discussion on the reverberatory model of short-term memory: a computational approach

Up to now a number of models have been proposed to underlie memory formation in the central nervous system. Two of these models are the reverberatory circuit model and the other one the self-feedback loop model. This paper considers these two models regarding their ability to preserve neural activity and to hold information. In the self-feedback loop model, the activity level of the loop output is computed regarding the short lasting initial input. In the reverberatory circuit model, the activity levels of the proposed two-layer network outputs were computed regarding the short lasting initial inputs of the network. In the self-feedback loop model, the activity level of the loop output changes with each reverberation until it reaches a specific limit and then remains at that level. In the reverberatory circuit model, the activity levels of the proposed two-layer network outputs display an oscillatory behavior. These models can preserve the input activity, but they change its level with each reverberation. Information carried by a single neuron is related to its activity level. Therefore these models change the information during the reverberation. Short-term memory must hold the information for a certain period of time, so these models cannot be proposed to underlie short-term memory formation.     

Ordered short-term memory differs in signers and speakers: implications for models of short-term memory

Capacity limits in linguistic short-term memory (STM) are typically measured with forward span tasks in which participants are asked to recall lists of words in the order presented. Using such tasks, native signers of American Sign Language (ASL) exhibit smaller spans than native speakers ([Boutla, M., Supalla, T., Newport, E. L., & Bavelier, D. (2004). Short-term memory span: Insights from sign language. Nature Neuroscience, 7(9), 997-1002]). Here, we test the hypothesis that this population difference reflects differences in the way speakers and signers maintain temporal order information in short-term memory. We show that native signers differ from speakers on measures of short-term memory that require maintenance of temporal order of the tested materials, but not on those in which temporal order is not required. In addition, we show that, in a recall task with free order, bilingual subjects are more likely to recall in temporal order when using English than ASL. We conclude that speakers and signers do share common short-term memory processes. However, whereas short-term memory for spoken English is predominantly organized in terms of temporal order, we argue that this dimension does not play as great a role in signers' short-term memory. Other factors that may affect STM processes in signers are discussed.