Specific-cue effects of interpolated movements on distance and location retention in short-term motor memory

A short-term motor retention paradigm was used to examine the effect of interpolated movements on the recall of individual distance- and location-cue information. Subjects were instructed to learn either a distance or a location cue during the execution of simple, discrete original movements. Interpolated movements were then made which varied and repeated distance and location either individually or jointly. Changes in variable, absolute, and algebraic error from immediate to delayed recall were totally determined by interpolation of the individual instructed cue. No added recall changes were produced by interpolation of noninstructed cues. The data were interpreted as supporting the presence of a stimulus-selection process that dissociates kinesthetic information as a function of instructional set. The effects of inter-poated movements, then, are determined partially by this selection process.     

Effect of ramp-like contours upon perceived size and detection threshold

Perceived widths and detection thresholds were measured for foveally viewed stimuli which were edged on two sides by luminance ramps. Perceived width approximated the distance between the midpoints of the ramps. It varied with the width of the ramps, but was unaffected by a five-fold change in the luminance of the stimulus. The detection threshold was higher for a ramp stimulus than for a normal stimulus of the same apparent width. The relationship between perceived width and detectability is consistent with a theoretical treatment based upon receptive-field mechanisms.     

The co-ordination of codes in short-term retention

The present experiments explored ways in which information encoded along different dimensions might be co-ordinated to determine memory performance. First, can an acoustic similarity decrement be offset by additional semantic encoding? Experiment I offers evidence for this compensatory interaction of codes. Second, does trade-off occur such that more information held in one code means less in another code? Third, are codes additive? Experiment II offers no support for the notion of a trade-off between encoding systems. However, when two codes were made available in the second study, recall was increased over the level achieved by either code alone.     

Temporal aspects of retrieval in short-term serial retention

In three experiments, temporal properties of memory retrieval are studied. Latency of positionally probed recall of a single item is measured as a function of its serial position (SP) in a serial list. The requested SP is indicated by a positional probe, presented immediately after the list. For two organizational structures of the list (i.e., grouped vs. ungrouped lists) the experiments study the effects of precueing the probe position briefly before probe presentation, the cue signal indicating the SPs relevant for recall. The problem of confounded effects on latency of requested SP and of probe-signal location is also investigated. A bow-shaped SP-curve is found for ungrouped lists; precueing reduces RT but does not affect the bowed shape. This argues against selective confounding effects of spatial probe position and also suggests that precueing preactivates memory access. Grouping the items into two sublists eliminates precueing effects for items around the group boundary. Furthermore, precueing is detrimental when SPs at opposite ends of the list are precued. This suggests that the available points of memory access can only be utilized one at a time, so that precueing is not beneficial when the item cannot be reached via the preactivated point. Although the notion of single access to memory is in accord with both positional cueing theory and non-associative hierarchical theories (e.g., Estes 1972), various details of the results are in favor of the first type of explanation.     

The alleviation of short-term retention decrements with reactivation

Retention of spatial information by rats was shown to decrease significantly over a 90-sec retention interval. However, this decrement was alleviated significantly when a reactivation or cueing treatment was presented during the 90-sec interval. Further, the rate of forgetting following reactivation was shown to be similar to that which occurs following original information input. The implications of these findings for information loss models of forgetting were discussed.     

Effects of cuing on short-term retention of order information

In two experiments, subjects recalled one of two letter sequences following a digit-filled retention interval. Recall performance was increased by precues informing subjects which letter sequence would be tested, and the cuing advantage remained throughout 60-digit retention intervals. No improvement was found, however, for cues occurring after the letters but before the digits. The cuing effects were attributed to encoding, not rehearsal, processes and were explained by a version of the Estes perturbation model, which included a long-term storage component and a fixed perturbation probability.     

The role of the interpolated task in short-term retention

It has been proposed that a single set of operations based on classical interference theory is adequate to describe the phenomena of both short- and long-term memory. An article by Keppel and Underwood (1962) argues that short-term forgetting is due to proactive interference and, by implication, not a result of trace decay. An experiment which varied retention interval and the nature of the interpolated task, gave results which indicate that when the amount forgotten and the nature of errors are considered, a decay model is supported, the proactive interference suggestion being untenable.