Essays in honour of William E. Hockley: A Festschrift.

A Festschrift (the German word standing for feast-script) is a collection of essays to celebrate the significant contributions of a scholar to their respective field of studies. Here, it is our honour to introduce this special issue of the Canadian Journal of Experimental Psychology as a Festschrift for William (Bill) E. Hockley to celebrate his rich scholarly contributions to the field of cognitive psychology, specifically on human memory.

Testing a Strategy-Disruption Account of the List-Strength Effect.

Presenting items multiple times on a study list increases their memorability, a process known as item strengthening. The list-strength effect (LSE) refers to the finding that, compared to unstrengthened (pure) lists, lists for which a subset of the items have been strengthened produce enhanced memory for the strengthened items and depressed memory for the unstrengthened items. Although the LSE is found in free recall (Tulving & Hastie, 1972), it does not occur in recognition (Ratcliff et al.

Diffusion modeling of interference and decay in auditory short-term memory.

Decay and interference are two leading proposals for the cause of forgetting from working and/or short-term memory, and mathematical models of both processes exist. In the present study, we apply a computational model to data from a simple short-term memory task and demonstrate that decay and interference can co-occur in the same experimental paradigm, and that neither decay nor interference alone can account for all cases of forgetting.

Listening to the Picture-Superiority Effect.

The picture-superiority effect (PSE) refers to the finding that, all else being equal, pictures are remembered better than words ( Paivio & Csapo, 1973 ). Dual-coding theory (DCT; Paivio, 1991 ) is often used to explain the PSE. According to DCT, pictures are more likely to be encoded imaginally and verbally than words.

Overwriting and intrusion in short-term memory.

Studies of interference in working and short-term memory suggest that irrelevant information may overwrite the contents of memory or intrude into memory. While some previous studies have reported greater interference when irrelevant information is similar to the contents of memory than when it is dissimilar, other studies have reported greater interference for dissimilar distractors than for similar distractors. In the present study, we find the latter effect in a paradigm that uses auditory tones as stimuli.

A shared short-term memory system for stimulus duration and stimulus frequency.

Recent research has suggested the existence of a modality-independent memory system that is responsible for storing representations of simple, scalar stimulus attributes, such as the frequency of an auditory pure tone or the duration of a stimulus. In the present study, we modify an existing computational model of short-term memory (STM) for stimulus frequency to allow it to perform STM tasks for both stimulus frequency and stimulus duration, supporting the notion of a common scalar STM system. We further demonstrate the utility of the model by showing that it can reproduce the subjective shortening effect, a classic finding in the psychophysical literature.

TMS-induced neural noise in sensory cortex interferes with short-term memory storage in prefrontal cortex.

In a previous study, Harris et al. (2002) found disruption of vibrotactile short-term memory after applying single-pulse transcranial magnetic stimulation (TMS) to primary somatosensory cortex (SI) early in the maintenance period, and suggested that this demonstrated a role for SI in vibrotactile memory storage. While such a role is compatible with recent suggestions that sensory cortex is the storage substrate for working memory, it stands in contrast to a relatively large body of evidence from human EEG and single-cell recording in primates that instead points to prefrontal cortex as the storage substrate for vibrotactile memory.

Does stimulus complexity determine whether working memory storage relies on prefrontal or sensory cortex?

Traditionally, working and short-term memory (WM/STM) have been believed to rely on storage systems located in prefrontal cortex (PFC). However, recent experimental and theoretical efforts have suggested that, in many cases, sensory or other task-relevant cortex is the actual storage substrate for WM/STM. What factors determine whether a given WM/STM task relies on PFC or sensory cortex? In the present article, we outline recent experimental findings and suggest that the dimensionality or complexity of the to-be-remembered property or properties of a stimulus can be a determining factor.

Irrelevant sensory stimuli interfere with working memory storage: evidence from a computational model of prefrontal neurons.

The encoding of irrelevant stimuli into the memory store has previously been suggested as a mechanism of interference in working memory (e.g., Lange & Oberauer, Memory, 13, 333-339, 2005; Nairne, Memory & Cognition, 18, 251-269, 1990).

The longer we have to forget the more we remember: The ironic effect of postcue duration in item-based directed forgetting.

The effects of the duration of remember and forget cues were examined to test the differential rehearsal account of item-based directed forgetting. In Experiments 1 and 2, cues were shown for 300, 600, or 900 ms, and a directed forgetting effect (better recognition of remember than forget items) was found at each duration. In addition, recognition of both remember and forget items increased with cue duration.

Associative and familiarity-based effects of environmental context on memory.

Previous research has shown that hit and false alarm rates and claims of remembering are greater when test items are shown in the same context that was present at study. In the present article, the effects of environmental context (photographs of scenes shown in the background) were evaluated in a yes-no recognition task when context was manipulated on the computer screen compared with when subjects were wearing virtual reality glasses (Experiment 1), in a forced-choice recognition task to address the question of criterion changes (Experiment 2), and in a free-recall task (Experiment 3) to address the issue of generality. The results show that both specific item-context associations and the familiarity of an old context influence memory performance.

Can vibrotactile working memory store multiple items?

Vibrotactile working memory is increasing in popularity as a model system to test theories of working memory. Notably, however, we know little about vibrotactile working memory capacity. While most other domains of working memory are able to store multiple items (for example, the seven-plus-or-minus-two capacity of verbal memory [17]), previous examinations of vibrotactile working memory suggest that stored items may suffer from high levels of interference in the form of overwriting or representation-based interference [2,4], potentially limiting capacity and also limiting our ability to draw comparisons between vibrotactile working memory and other forms of working memory.

Diffusion modeling of interference in vibrotactile working memory.

The nature of interference in working memory has been a subject of discussion for decades. It has previously been argued that irrelevant stimuli can interfere with working memory by being encoded into memory. Previous findings have suggested that irrelevant sensory activity can interfere with the storage of information in tactile working memory.

Mechanisms of interference in vibrotactile working memory.

In previous studies of interference in vibrotactile working memory, subjects were presented with an interfering distractor stimulus during the delay period between the target and probe stimuli in a delayed match-to-sample task. The accuracy of same/different decisions indicated feature overwriting was the mechanism of interference. However, the distractor was presented late in the delay period, and the distractor may have interfered with the decision-making process, rather than the maintenance of stored information.