An asymmetrical effect of similarity in the attenuation of stimulus suffix interference

The Basis and Implications of the Restoration of a Recency Effect in Immediate Serial Recall

When a spoken presentation of a supra-span sequence of to-be-remembered (TBR) items is followed immediately by a similarly-spoken non-TBR item (stimulus suffix) the typical salience of the terminal item in recall is almost destroyed. However, Salter (1975) observed restoration of salience when pre-terminal and terminal TBR items differed in category membership. Five experiments are reported which aimed to clarify the basis and locus of Salter's effect. Survival of salience for the heterogeneous item was found under the following conditions: with the occurrence of the item unpredictable from trial-to-trial (Experiment I); with enforced processing of the suffix (Experiment II); with performance of a secondary task during list presentation (Experiment III); with the requirement to retain both the location and identity of the item (Experiment IV); and with the item as the terminal member of a non-suffixed visual list (Experiment V). It is argued that the effect has a postcategorical locus, and that its origin is not in better registration (mediated by selective attention), but, rather, in the enhancement of retrieval (mediated by access to distinctive information encoded during presentation). It is suggested that the latter hypothesis may have wide application in accounting for many kinds of salience.

A Test of Precategorical and Attentional Explanations of Speech Suffix Interference

It is well-known that a redundant item or “stimulus suffix”, which does not have to be recalled, which is spoken, and which terminates the presentation of a beyond span-length sequence of to-be-remembered (TBR) spoken items, will generate considerable interference in immediate serial recall. Previous work has established that speech suffix interference is not influenced by a number of intrinsic attributes of the suffix. A limitation of this work, however, is the fact that in each study there has been little if any disparity between TBR sequence and suffix in terms of extrinsic attributes. Experiment I extends this work and showed that at least one intrinsic attribute of the suffix (personal significance) has no effect on suffix interference when there is also a marked disparity between TBR sequence and suffix in terms of one specific extrinsic attribute (spatial location). Experiment II simply served to eliminate one possible artifactual explanation of this finding. The result appears to have some theoretical importance since it is inconsistent with Kahneman's (1973) attentional account of suffix interference and with one interpretation of a precategorical hypothesis due to Morton, Crowder and Prussin (1971).

“Next-to-nothings” and Nothingness: A Study of Attention, Attenuation and the Stimulus Prefix Effect

The stimulus prefix effect, in which a non-recallable item placed at the beginning of a to-be-remembered string of items creates interference, was studied using a 1-s simultaneous visual method of presentation. Two variants on the standard prefix condition were used; in one, the prefix, o, was presented in a different colour from the memory string of seven digits and, in the other, the prefix consisted of three identical zeroes. The three prefix conditions were compared with two control conditions in which either seven or eight digits were presented. No evidence of prefix effects was found in the recall data over serial positions 1–4, for which retrieval was highly efficient, and it was concluded that the action of response set may exclude the prefix from a response buffer (c.f. Morton, 1970). There was also no evidence that the specialized prefixes led to an attenuation of the interference found in the remaining positions. The latter finding is considered to be contrary to a unit-formation hypothesis (Kahneman, 1973) but is consistent with a mode of operation of the logogen model (Morton, 1970).

Recency and suffix effects with immediate recall of olfactory stimuli

In contrast to our understanding of the immediate recall of auditory and visual material, little is known about the corresponding characteristics of short-term olfactory memory. The current study investigated the pattern of immediate serial recall and the associated suffix effect using olfactory stimuli. Subjects were trained initially to identify and name correctly nine different odours. Experiment 1 established an immediate correct recall span of approximately six items. In Experiment 2 participants recalled serially span equivalent lists which were followed by a visual, auditory, or olfactory suffix. Primacy was evident in the recall curves for all three suffix conditions. Recency, in contrast, was evident in the auditory and visual suffix conditions only; there was a strong suffix effect in the olfactory suffix condition. Experiment 3 replicated this pattern of effects using seven-item lists, and demonstrated that the magnitude of the recency and suffix effects obtained in the olfactory modality can equate to that obtained in the auditory modality. It is concluded that the pattern of recency and suffix effects in the olfactory modality is reliable, and poses difficulties for those theories that rely on the presence of a primary linguistic code, sound, or changing state as determinants of these effects in serial recall.

Modality effects and the structure of short-term verbal memory

The effects of auditory and visual presentation upon short-term retention of verbal stimuli are reviewed, and a model of the structure of short-term memory is presented. The main assumption of the model is that verbal information presented to the auditory and visual modalities is processed in separate streams that have different properties and capabilities. Auditory items are automatically encoded in both the A (acoustic) code, which, in the absence of subsequent input, can be maintained for some time without deliberate allocation of attention, and a P (phonological) code. Visual items are retained in both the P code and a visual code. Within the auditory stream, successive items are strongly associated; in contrast, in the visual modality, it is simultaneously presented items that are strongly associated. These assumptions about the structure of short-term verbal memory are shown to account for many of the observed effect of presentation modality.

An "across-the-board" modality effect in immediate serial recall

A serial recall experiment comparing visual and auditory presentation is reported which demonstrates that, under certain conditions, there is an auditory advantage in the pre-recency (1–6) as well as the recency (7–8) serial positions. Presentation modality was combined factorially with five levels of a concurrent writing task, which had to be completed for each to-be-remembered digit during presentation: NC, no concurrent task; XX, writing two crosses; DX, writing each digit followed by a cross; XD, the converse of DX; and DD, writing each digit twice. When presentation was visual, there was a monotonic (non-decreasing) trend in the recall errors going from NC to DD (in above order) for both the pre-recency and recency positions on average. With an auditory presentation, however, the trend was more gradual, though still monotonic. For the pre-recency items, an auditory advantage was obtained with conditions XX, XD and DD, but not for NC and DX. Additionally, with an auditory presentation, there was no evidence of a difference between NC and XX, nor between DX and XD. It is argued that both pre-categorical acoustic storage and residual activation effects, engendered in a logogen system (Morton, 1970) by the repetition “structure” of the concurrent tasks, helped to determine the attentional capacity available for secondary (elaborative) rehearsal and, in turn, set the levels of recall.