Preselection in short-term motor memory.

Recent studies by Jones (1974) have posited that accurate movements in short-term motor memory (STMM) are mediated by the subject's ability to preset effector mechanisms and monitor their efferent output. Three experiments were conducted to examine this hypothesis. Experiment 1 involved comparisons between the reproduction of the end-location and the reproduction of the distance of a preselected movement. The results revealed that preselected location was superior to preselected distance, indicating that the efference attached to movement extent was not primary. Experiment 2 examined whether location cues were primarily encoded independent of the movement presentation mode. The subjects recalled target locations under preselected, constrained, and passive movement conditions. Recall in the preselected condition was superior to that in the constrained and passive conditions, which showed no difference, suggesting that afferent location information per se was not totally responsible for recall accuracy. Experiment 3 examined the processing requirements of preselected, constrained, and passive location information by filling the retention interval with interpolated processing activity. While preselected location was clearly superior, the three conditions were not differentially affected by processing activity. These overall findings were interpreted as contrary to Jones (1974) and pointed to the importance of preselection in short-term motor memory.     

Cognitive Strategies and Short-term Memory for Movement Distance and Location

A number of researchers (e.g. Kerr, 1978; Walsh, Russell, Imanaka, & James, 1979) have previously demonstrated interference between location and distance information in motor short-term memory. This interference manifests itself in a characteristic pattern of undershooting and overshooting, with reproduction movement location being drawn in the direction of criterion movement distance and, conversely, the distance of reproduction movements being influenced by the terminal location of the criterion movement. We investigated the effects of different cognitive strategies upon the appearance of this location-distance interference during the reproduction of movement location (Experiment 1) and distance (Experiments 2 and 3) in a linear arm positioning task. Experiment 1 compared performance in location reproduction between two strategy groups differing in the availability of explicit information about the change in starting position. The characteristic undershooting-overshooting interference pattern was observed for the group without the explicit information about the change in starting position but disappeared for the group in which explicit information about the change in starting position was provided. Experiment 2 examined the systematic undershooting-overshooting pattern in distance reproduction for a location strategy (involving some extrapolation of the start and end locations), a counting strategy, and a distance sense strategy (involving the use of visual imagery). The systematic response bias pattern disappeared when the subjects used a location strategy but was clearly observed for the subjects using the other two strategies. This finding was generally confirmed by Experiment 3, which showed a typical undershooting-overshooting pattern in distance reproduction for a counting/distance sense strategy but not for two location strategies (a general location and an explicit location strategy). The location strategies differed in the availability of explicit information about starting and end locations for both the criterion and reproduction movements. The results from these three experiments indicate that explicit information about the start andlor end locations prevents the usual interference between location and distance information from arising in movement reproduction. The notions of automatic and controlled processing and cerebral hemispheric specialization are discussed as potential explanations of these results and of the interference typically observed in motor short-term memory between distance and location information.     

The Effect of Interpolated Motor Activity on the Short-Term Retention of Movement Distance and End-Location

The effect of an interpolated movement on the recall of a blind, lever-positioning movement was assessed separately for the reproduction cues of distance and end-location. Both cues showed the context effect of assimilation, that is, the end-location of the interpolated movement caused directional biasing of the algebraic or constant error (CE) for location reproduction while the length of the interpolated movement caused similar directional biasing for distance reproduction. Variability about algebraic error (VE) was used to assess forgetting. There was no change in VE for location reproduction, and an increase in VE for distance reproduction was limited to the relatively large movements. Thus, an interpolated movement that does not have to be remembered does not cause interference with the retention of location information, but does cause some interference with the retention of distance information. The findings are discussed in relation to a model of motor short-term memory which incorporates both CE and VE.     

Interference Between Location and Distance Information in Motor Short-Term Memory: The Respective Roles of Direct Kinesthetic Signals and Abstract Codes

Interference between location and distance information in motor short-term memory has been hypothesized on the basis of the systematic pattern of undershooting and overshooting in movement reproduction that occurs when the starting position for reproduction movements is shifted. To determine the possible contribution of limb-specific kinesthetic information to this systematic undershooting-overshooting pattern, we compared the reproduction of linear arm positioning movements performed under either same-limb or switched-limb conditions. Ten subjects were assigned to either a location or distance cue condition, and each subject completed a total of 40 trials, 20 under same-limb and 20 under switched-limb conditions. Each trial consisted of criterion and reproduction movements, separated by a 10-s retention interval. The starting position for the reproduction movement was shifted by 0, 2, or 4 cm in either direction from that of the criterion movement. The systematic undershooting-overshooting pattern, which occurs when either the movement location or distance is reproduced, arose under both the same-limb and switched-limb conditions, suggesting that the primary cause of the location-distance interference is not limb-specific kinesthetic information. Rather, more abstract information in the form of a conceptual memory code appears to be the probable cause of the location distance interference phenomenon.     

Dissociating cognitive and motor interference effects on kinesthetic short-term memory

In two experiments, we investigated how short-term memory of kinesthetically defined spatial locations suffers from either motor or cognitive distraction. In Exp. 1, 22 blindfolded participants moved a handle with their right hand towards a mechanical stop and back to the start and then reproduced the encoded stop position by a second movement. The retention interval was adjusted to approximately 0 and 8 s. In half of the trials participants had to provide a verbal judgment of the target distance after encoding (cognitive distractor). Analyses of constant and variable errors indicated that the verbal judgments interfered with the motor reproduction only, when the retention interval was long. In Exp. 2, 22 other participants performed the same task but instead of providing verbal distance estimations they performed an additional movement either with their right or left hand during the retention interval. Constant error was affected by the side of the interpolated movement (right vs. left hand) and by the delay interval. The results show that reproduction of kinesthetically encoded spatial locations is affected differently in long- and short-retention intervals by cognitive and motor interference. This suggests that reproduction behavior is based on distinct codes during immediate vs. delayed recall.     

Presentation- and test-trial effects on acquisition and retention of distance and location

Acquisition and retention effects of presentation and test trials on movement distance (Experiment 1) and location (Experiment 2) were examined under three multitrial training methods. Three groups of 15 government employees performed three training trial cycles consisting of six trials each. Training methods emphasized either presentation-trial repetition, test-trial repetition, or presentation- and test-trial alternation within cycles. After training, both short- (3 min.) and long-term (24 hr.) retention scores were recorded. Absolute error revealed that (a) presentation-trial repetition promoted acquisition of both distance and location but resulted in extensive short- and long-term forgetting; (b) test-trial repetition produced error increases within cycles, potentiated presentation-trial effectiveness during acquisition, and enhanced long-term retention of both distance and location; (c) presentation- and test-trial alternation promoted distance and location acquisition and produced distance retention intermediate to that of the other two methods. Experiment 3 provided data to support the interpretation that test-trial retention benefits are a function of movement execution mode.     

Attentional requirements for location and distance of movement: encoding and recognition

The purpose of this experiment was to study the early processing stages of encoding and recognition of slow movement in a short-term motor-memory paradigm. These stages were examined by determining whether Laabs' (1973) differential decay rates for location of movement and distance of movement could be replicated when the interfering activity was performed during the criterion and replication movements. 20 subjects performed a linear-positioning task in a 2 X 2 X 2 (count X movement type X retention interval) experimental design. 10 subjects in one condition counted backwards by 3s during the criterion and replication movements. There were no detrimental effects for location and distance-cue reproduction when attention was shared with counting backwards. Like Laabs' results, location of movement was maintained over the 15-sec. interval while distance of movement spontaneously changed. These results supported the notion that the early stages of encoding and recognition of cues for movement can occur unaffected by a secondary task.     

Retention Characteristics of Motor Short-Term Memory Cues

The retention characteristics of several cues thought to underlie movement reproduction ability were examined and the results were discussed in terms of two models of motor short-term memory (Laabs, 1973; Pepper & Herman, 1970). Trace decay was indexed by constant error and not variable error. It appeared that the movement cues studied all had access to the central processing capacity in that forgetting did not occur until rehearsal was blocked by the introduction of a secondary task. However, there was some evidence to indicate that different cues are centrally represented in varying degrees of exactness. In this respect reliance on active movement cues and location cues produced better reproduction than passive movement and distance cues, respectively. The existence of an adaptation level established from the range of movement utilized was supported, and short movements were more dependent on central processing capacity than were long movements.     

Memory for Constrained and Preselected Movement Location and Distance

These experiments assessed the interrelationship between location and distance cues in the coding of movements. In separate experiments subjects recalled either the terminal location or the distance of constrained (Experiment 1) or preselected (Experiment 2) movements following a 15-sec retention interval. Changes in direction amd amplitude of starting position were used to ascertain whether recall errors were related to these changes. The findings of both experiments indicated that location and distance were recalled with similar accuracy when the starting position was identical for the criterion and recall movement. However, analysis of constant errors when the recall starting position was varied in either direction clearly indicated neither terminal location nor distance are coded independently, and memory for movement is based on an interaction between these cues.     

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.     

An Empirical Note on the Role of Verbal Labels in Motor Short-Term Memory Tasks

Previous studies of motor short-term memory have shown that when a criterion movement on a semicircular positioning task is accompanied by an appropriate verbal label (a clock-face position), recall of the movement is more accurate than when only the movement is presented. This increased accuracy could be due to either the additional spatial information provided by the label or enhanced retention of the movement information. These two alternatives cannot be distinguished on the basis of previous studies because the studies have not evaluated movement accuracy following presentation of the label alone. The present study employed such a condition in addition to the movement-only and movement-plus-label conditions to distinguish between the two hypotheses. In all conditions, subjects were asked to move to the criterion position after a retention interval of either 5 sec or 60 sec. Evidence indicated that subjects who received both the label and the movement tended to use the spatial information provided by the label at the 60-sec interval. The evidence did not indicate that the verbal label actually enhanced retention of the movement information.     

An empirical note on the role of verbal labels in motor short-term memory tasks

Previous studies of motor short-term memory have shown that when a criterion movement on a semicircular positioning task is accompanied by an appropriate verbal label (a clock-face position), recall of the movement is more accurate than when only the movement is presented. This increased accuracy could be due to either the additional spatial information provided by the label or enhanced retention of the movement information. These two alternatives cannot be distinguished on the basis of previous studies because the studies have not evaluated movement accuracy following presentation of the label alone. The present study employed such a condition in addition to the movement-only and movement-plus-label conditions to distinguish between the two hypotheses. In all conditions, subjects were asked to move to the criterion position after a retention interval of either 5 sec or 60 sec. Evidence indicated that subjects who received both the label and the movement tended to use the spatial information provided by the label at the 60-sec interval. The evidence did not indicate that the verbal label actually enhanced retention of the movement information.     

Effect of starting position on reproduction of movement: further evidence of interference between location and distance information

Two experiments done with a short-term memory paradigm examined the influence of shifts in the starting position on the reproduction of kinesthetic location (Exp. 1) and on distance cues (Exp. 2). We assessed possible causes of the systematic pattern of undershooting and overshooting as related to the shift in the starting position. In each experiment, two groups of 10 students were given 25 trials, and each had criterion and reproduction tasks involving linear-positioning movements with a 10-sec. retention interval. Each experiment had two independent variables, the group of subjects and the shift in the starting position. The two groups differed in the possible sources of information, the distance moved (Exp. 1) or the end-location (Exp. 2), which were assumed to cause undershooting and overshooting during reproduction. Analysis showed that the information about the distance moved may produce undershooting and overshooting in reproduction of the end-location (Exp. 2). Also, the information about the end-location may produce undershooting and overshooting in reproduction of the distance moved (Exp. 2). The findings were further evidence of interference between location and distance cues in motor short-term memory.     

A motor isolation effect: When object manipulability modulates recall performance

Previous studies suggested that the language production architecture is recruited during verbal retention, and others proposed that spatial memory relies on the oculomotor system. The objective of the present study was to investigate the role of the motor system in object memory, by examining the effect of objects' affordances on retention. In a serial recall task, we manipulated the manipulability of objects to retain in memory. We used an isolation paradigm where we isolated the manipulability level of one object from the list. We showed that recall performance improved for the isolated object (Experiment 1) and that this advantage was abolished when participants were required to perform motor suppression during the task (Experiment 2). In Experiment 3, we showed that the abolition of the motor isolation effect in Experiment 2 was not due to an effect of distraction since motor suppression was shown not to interfere with a semantic isolation effect. It is argued that motor affordances play a role in object memory, but only when the motor characteristics of an object allow discriminating it from the other objects in the list.     

Target location effects in tapping tasks

Previous experiments on tracking have shown that target location (measured in terms of the distance of the target from the boundary circumscribing the area of movement) affects the speed and accuracy of movement. The present experiment examined the effects of boundary distance on the speed and accuracy of tapping. Subjects performed on two-, three- and five-position tasks varying in movement amplitude and target width. Results showed that movement time increased, and constant error became more positive as boundary distance increased. These results differed from those found in respect of pursuit tracking in that constant error was affected and not variable error. They increase the generality of the finding that motor performance varies with target location, and they support theories of motor control implicating target location.     

The memory representation of motor skills: a test of schema theory

Currently, a popular model for the central representation of motor skills is embodied in Schmidt's schema theory of discrete motor skill learning (Schmidt, 1975). Two experiments are reported here that contrast predictions from a schema abstraction model that is the basis for schema theory with those from an exemplar-based model of motor skill memory representation. In both experiments, subjects performed 300 trials per day of three variations of a three-segment timing task over 4 days of acquisition. The subjects then either immediately transferred to four novel variations of the same task (Experiment 1) that varied in degree of similarity to the exemplars experienced during acquisition; or performed two novel and two previously produced exemplars, following 24-h and 1-week retention intervals (Experiment 2). The results indicated that novel task transfer was not affected by the degree of similarity between the acquisition and transfer exemplars, and that there was no advantage for a previously produced exemplar over a novel exemplar after either a 24-hr or 1 week retention interval. Also, in both experiments, a consistent pattern of bias in responding was noted for novel task transfer and retention. These results are indicative of a schema abstraction model of memory representation for motor skills.     

The Use of Location and Distance in Reproducing Different Amplitudes of Movement

Experiments have demonstrated that in order to reproduce a standard movement, subjects can move for a certain distance or move to a certain location. Available evidence tentatively suggests the use of distance for short movements and location for long movements. However, this evidence is in conflict with the motor short-term memory characteristics of short and long movements. An experiment is reported which demonstrates that subjects spontaneously use distance for short movements and location for long movements, the procedure adopted being to shift by small amounts the starting-point of the estimation movements and test for a consequent shift in the end-point of the estimation. The experiment also revealed that using distance or location to reproduce a 40° movement resulted in equal accuracy, suggesting that the use of large amplitudes of movement has caused previous investigators to find that distance is less accurate than location.     

Working memory for ballet moves and spatial locations in professional ballet dancers

The aim of the present study was to investigate working memory for ballet moves in expert dancers. Experiment 1 showed that a concurrent spatial task did not interfere with the recall of a sequence of ballet moves when these were encoded alone without being associated with spatial locations. Experiment 2 showed that a concurrent motor task selectively interfered with the recall of ballet moves while neither a concurrent motor task nor a spatial task affected recall of the specific locations where each ballet move had to be performed. Experiment 3 showed that spatial interference affected recall of sequences of locations when these were encoded alone. Finally, in Experiment 4, a similarity effect for patterned ballet movements was shown. Taken together results show that spatial interference does not affect short‐term memory for ballet moves thus suggesting that working memory might contain a system for motor configurations. Copyright © 2009 John Wiley & Sons, Ltd.