An isolation effect in serial memory for spatial information

This paper reports the first demonstration of an isolation effect or von Restorff effect (von Restorff, 1933 von Restorff, H. 1933. Uber die Wirkung von Bereichsbildungen im Spurenfeld [On the effect of spheres formations in the trace field]. Psychologische Forschung, 18: 299–342. [Crossref] , [Google Scholar]) in the context of a spatial-memory task: Short-term serial recall was enhanced for both the location and the serial position of one red dot presented amongst a sequence of otherwise black dots. When the serial position of the isolate was fixed, the spatial isolation effect only emerged when participants received a control block of trials before the block of isolation trials (Experiment 1). However, when the serial position of the isolate was varied across isolation trials, an isolation effect was still produced regardless of condition order (Experiment 2). It is suggested that both temporal grouping strategies and greater item-specific processing may have contributed to the enhanced retention of the isolate.     

Distinctiveness in serial memory for spatial information

Several studies have shown that recall performance depends on the extent to which an item differs from other items in a sequence (the distinctiveness effect; see, e.g., Kelley & Nairne, 2001). Distinctiveness effects, however, have been demonstrated mainly in the verbal domain. The present study extends distinctiveness effects to the spatial domain. In two experiments, participants recalled the order in which series of spatially located dots had been presented. Item discriminability was varied within the sequence by manipulating the duration of the interval inserted between the presentation of the dots (Experiment 1) and the perceptual characteristics of the stimuli (Experiment 2). The results showed that these manipulations in the spatial domain produce distinctiveness effects similar to those observed with verbal material (see, e.g., Neath & Crowder, 1990) and suggest that distinctiveness models of memory should take into account the processing of spatial information.     

Asymmetric binding in serial memory for verbal and spatial information

As the number of studies showing that items can be retained as bound representations in memory increases, researchers are beginning to investigate how the different features are bound together. In the present study, we examined the relative importances of the verbal and spatial features in serial memory for visual stimuli. Participants were asked to memorize the order of series of letters presented visually in different locations on the computer screen. The results showed that manipulating the phonological similarity of the letters affected recall of their spatial locations, but that increasing the complexity of the spatial pattern had no effect on recall of the letters. This finding was observed in both order reconstruction (Exps. 1 and 2) and probe serial recall (Exps. 3 and 4), suggesting that verbal–spatial binding in serial memory for visual information is asymmetric.     

A spatial modality effect in serial memory

In 2 experiments, the authors tested whether the classical modality effect-that is, the stronger recency effect for auditory items relative to visual items-can be extended to the spatial domain. An order reconstruction task was undertaken with four types of material: visual-spatial, auditory-spatial, visual-verbal, and auditory-verbal. Similar serial position curves were obtained regardless of the nature of the to-be-remembered sequences, with the exception that a modality effect was found with spatial as well as with verbal materials. The results are discussed with regard to a number of models of short-term memory.     

Transitional information in spatial serial memory: path characteristics affect recall performance

This study examined the role of stimulus characteristics in a visuospatial order reconstruction task in which participants were required to recall the order of sequences of spatial locations. The complexity of the to-be-remembered sequences, as measured by path crossing, path length, and angles, was found to affect serial memory, in terms of both recall accuracy and response times. The results demonstrate that not all sequences are remembered equally and that spatial characteristics of the sequences constitute an important variable in the understanding of visuospatial serial memory. More important, the data suggest that spatial path represents transitional information and that, as is the case in verbal serial memory, transitional information is of critical importance in serial memory.     

Temporal grouping in auditory spatial serial memory

Grouping effects in serial recall have been widely studied with verbal stimuli, but hardly ever with spatial stimuli and not at all with auditory spatial stimuli. In Experiment 1, we examined the influence of combined temporal and pitch grouping on recall of the locations from which bursts of white noise were presented. Similar to findings in verbal studies, effects of the grouping manipulation were found in performance accuracy, in the nature of order errors, and in the timing of responses. Experiment 2 was designed to distinguish the role played by pitch grouping from that played by temporal grouping, through independent manipulation of the presence of a shift in pitch and that of a temporal gap. The results showed that the temporal grouping manipulation determined performance and the pitch grouping manipulation did not. Similarities between our findings and those of verbal studies, and implications for the understanding of serial memory are discussed.     

The effect of path length and display size on memory for spatial information

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.     

The representation of spatial information in memory

Following memorisation of the spatial arrangement of an array of circles, subjects were asked to recall the circles in a type of free-recall task designed to determine the structure of the memorised information. Their performance showed that the circles tended to be recalled in an order that corresponded with a top-to-bottom ordering of circles on the array. In a second experiment the input order of the circles was varied by presenting them successively. The results indicated that input order influenced recall order. The implications for hypotheses about the structure and manipulation of stored spatial information were discussed.     

Rehearsal in serial memory for visual-spatial information: Evidence from eye movements

It is well established that rote rehearsal plays a key role in serial memory for lists of verbal items. Although a great deal of research has informed us about the nature of verbal rehearsal, much less attention has been devoted to rehearsal in serial memory for visual-spatial information. By using the dot task—a visual-spatial analogue of the classical verbal serial recall task—with delayed recall, performance and eyetracking data were recorded in order to establish whether visual-spatial rehearsal could be evidenced by eye movement. The use of eye movement as a form of rehearsal is detectable (Experiment 1), and it seems to contribute to serial memory performance over and above rehearsal based on shifts of spatial attention (Experiments 1 and 2).     

When distractors and to-be-remembered items compete for the control of action: a new perspective on serial memory for spatial information

In serial memory for spatial information, performance is impaired when distractors are interpolated between to-be-remembered (TBR) stimuli (Tremblay, Nicholls, Parmentier, & Jones, 2005). The so-called sandwich effect, combined with the use of eye tracking, served as a tool for examining the role of the oculomotor system in serial memory for spatial information. Participants had to recall the order in which sequences of TBR locations were presented. In some trials, to-be-ignored blue dots were presented after each TBR location. Our results show that response locations shift toward the location of the distractors, and this deviation is related to the eye movement deviation toward the distractor location. These results suggest that TBR and to-be-ignored locations are encoded onto a common map that could lie within the oculomotor system. Interference in memory for spatial information is interpreted in light of a model of oculomotor behavior (Godijn & Theeuwes, 2002b).     

Exploring the suffix effect in serial visuospatial short-term memory

The suffix effect—the loss of recency induced by a redundant end-of-list item—was studied in a visuospatial serial recall task involving the memory for the position of dots on a screen. A visuospatial suffix markedly impaired recall of the last to-be-remembered dot. The impact on recall was roughly of equal magnitude whether the suffix shared attributes with the to-be-remembered dots (Experiment 1) or was visually distinct (Experiments 2 and 3). Although the presence of a tone suffix also impaired serial memory for the last items in the sequence, the impact of a visuospatial suffix was more marked, implying a specific as well as a possible general effect of suffix in the visuospatial domain (Experiment 4). The suffix effect seems not to be a phenomenon confined to verbal material but rather a universal phenomenon possibly related to grouping.     

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.     

The avian hippocampus and short-term memory for spatial and non-spatial information

Three experiments investigated the role of the pigeon hippocampal formation (the hippocampus and area-parahippocampalis) in short-term memory for non-spatial and spatial information. The acquisition of delayed matching-to-sample and the short-term retention of non-spatial visual information, using a small set of sample stimuli, were unaffected by aspiration lesions of the hippocampus or the neostriatum (Experiment 1). Similarly, acquisition and short-term retention of non-spatial information using a successive, trial-unique, delayed non-matching-to-sample procedure were unaffected by hippocampal damage; the same birds had, however, displayed a profound autoshaping impairment (Experiment 2). Acquisition of a spatial delayed matching-to-sample task was unimpaired by hippocampal damage. However, lesioned animals were impaired following the introduction of retention intervals on this procedure (Experiment 3). The correspondence between the behavioural effects of hippocampal lesions in birds and mammals on short-term memory is discussed, and the implications of these results for avian hippocampal function are considered.     

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.     

A revised spatial serial learning and memory procedure using Corsi's Block-tapping apparatus

The purpose of this study was to use Corsi's Block Tapping Test as a spatial analog of Benton's Serial Digit Learning Test, using the cognitive neuroscience approach utilized in the California Verbal Learning Test. 60 normal participants, ages 19-52 years, were included and administered an 8-block sequence for 9 trials or until they recalled the entire sequence for 3 consecutive errorless trials. The score was the number of blocks tapped in the correct serial order. An interference trial was administered. Following a 10-min. delay, free recall of the original sequence, cued recall, and recognition measures were obtained. Retroactive interference was significant, but no proactive interference emerged. Scores showed a strong primacy effect. Most participants who learned the sequence to the criterion of three successive errorless trials recalled the sequence after the 10-min. delay. Scores on the cued recall and recognition trials tended to support their validity as less demanding retrieval tasks. The use of this spatial learning and memory procedure allows finer discriminations among nonverbal memory deficits and may facilitate direct comparisons with scores on verbal memory tasks such as Serial Digit Learning and the California Verbal Learning Test.     

The unimportance of explicit spatial information in serial recall of visually presented lists

The superiority of auditory over visual presentation in short-term serial recall may be due to the fact that typically only temporal cues to order have been provided in the two modalities. Auditory information is usually ordered along a temporal continuum, whereas visual information is ordered spatially, as well. It is therefore possible that recall following visual presentation may benefit from spatial cues to order. Subjects were tested for serial recall of letter-sequences presented visually either with or without explicit spatial cues to order. No effect of any kind was found, a result which suggests (a) that spatial information is not utilized when it is redundant with temporal information and (b) that the auditory-visual difference would not be modified by the presence of explicit spatial cues to order.     

Binding serial order to representations in working memory: a spatial/verbal dissociation

Verbal information is coded naturally as ordered representations in working memory (WM). However, this may not be true for spatial information. Accordingly, we used memory span tasks to test the hypothesis that serial order is more readily bound to verbal than to spatial representations. Removing serial-order requirements improved performance more for spatial locations than for digits. Furthermore, serial order was freely reproduced twice as frequently for digits as for locations. When participants reordered spatial sequences, they minimized the mean distance between items. Participants also failed to detect changes in serial order more frequently for spatial than for verbal sequences. These results provide converging evidence for a dissociation in the binding of serial order to spatial versus verbal representations. There may be separable domain-specific control processes responsible for this binding. Alternatively, there may be fundamental differences in how effectively temporal information can be bound to different types of stimulus features in WM.     

The floor effect: Impoverished spatial memory for elevator buttons

People typically remember objects to which they have frequently been exposed, suggesting that memory is a by-product of perception. However, prior research has shown that people have exceptionally poor memory for the features of some objects (e.g., coins) to which they have been exposed over the course of many years. Here, we examined how people remember the spatial layout of the buttons on a frequently used elevator panel, to determine whether physical interaction (rather than simple exposure) would ensure the incidental encoding of spatial information. Participants who worked in an eight-story office building displayed very poor recall for the elevator panel but above-chance performance on a recognition test. Performance was related to how often and how recently the person had used the elevator. In contrast to their poor memory for the spatial layout of the elevator buttons, most people readily recalled small distinctive graffiti on the elevator walls. In a more implicit test, the majority were able to locate their office floor and the eighth floor button when asked to point toward these buttons when in the actual elevator, with the button labels covered. However, identification was very poor for other floors (including the first floor), suggesting that even frequent interaction with information does not always lead to accurate spatial memory. These findings have implications for understanding the complex relationships among attention, expertise, and memory.