Jean McConnell

Irrelevant Pictures in Visual Working Memory

The aim of the paper is to establish firmly the phenomenon of an irrelevant picture effect and to demonstrate that the phenomenon can be used to investigate the characteristics of the visuo-spatial sketchpad. Experiment 1 introduces the use of dynamic visual noise as an interfering technique. This technique is shown to cause interference with a word list learned under visual mnemonic mediation instructions but to cause no interference when the word list is learned under verbal mediation instructions. Experiment 2 serves both to replicate this selective interference effect and to illustrate how the dynamic visual noise technique can be used to characterize further the nature of interference in the visuo-spatial sketchpad. Experiment 3 confirms the robustness of the dynamic visual noise technique. Additionally, this experiment demonstrates a double dissociation between two types of interference, dynamic visual noise and irrelevant speech, and two types of mediation, rote and visual mnemonic.

Interference in Visual Working Memory

This paper uses the theoretical distinction that has recently developed between the passive visual store and the active spatial rehearsal mechanism of the visuo-spatial component of working memory (VSSP). It examines the circumstances under which visual fields gain functional access to the passive visual store and seeks to cast light on the circumstances under which irrelevant visual fields interfere with concurrent visual processing. Experiment 1 contrasts a dynamic visual noise field with a static noise field and shows that the static field, in contrast to the dynamic noise field, causes no interference when presented concurrently with a visual task. Experiment 2 investigates the reason for this contrast and concludes that the static field is susceptible to decay and so fails to cause interference. Experiment 3 investigates further the circumstances under which dynamic visual noise causes interference and shows that manipulation of the number of changes within the noise field is also of importance in causing interference. The results allow further consideration of the characteristics of the VSSP.

The interval for interference in conscious visual imagery.

Three experiments are described that use dynamic visual noise (DVN) to interfere with words processed under visual and verbal processing instructions. In Experiment 1 DVN is presented to coincide with the encoding of the words or to coincide with the interval between encoding and recall. The results show that while DVN is a robust disruptor when it is applied during encoding to words processed under visual instruction, it has no effect during encoding when the words are processed under rote instruction. Moreover, DVN has no effect when it is applied during the retention interval, no matter what means are employed to encode the words. Experiment 2 extends these findings by again showing no effect of DVN during the retention interval, yet showing robust interference effects for visually processed words during recall. Finally, Experiment 3 demonstrates that the results of Experiments 1 and 2 cannot be explained by a difference in the time duration associated with application of DVN during the retention interval compared to during encoding and recall. Moreover, the differing decay functions for visually and verbally processed words during the intervals used in Experiment 3 suggest that any failure to cause interference is not because the two processing instructions resulted in words being retained in the same medium. The functions are consistent with word storage mechanisms reflecting appropriately verbal and visual properties. The results are discussed in terms of current models of visual working memory. It is argued that a full interpretation of the results requires a buffer mechanism as an important component of any model of visual working memory.

Complexity factors in visuo‐spatial working memory

Three experiments are presented that use a technique of selective interference—irrelevant pictures—to develop our understanding of visuo‐spatial working memory. Visual noise fields are used as the irrelevant pictures. Using two related measures of simple visual complexity, the experiments demonstrate that the greater the complexity the greater the degree of interference, even within a paradigm where subjects are instructed to look at but otherwise ignore the irrelevant pictures. Both the number of dots and the density of the dots comprising the visual noise fields affect the degree of interference in a concurrent memory task. In addition, increasing the size of the field increases the amount of interference. It is argued that the results give insight into the properties of visual working memory and contribute to its theoretical development. For example, it is argued that the store is directly accessible by externally presented interference and that particular aspects of the noise displays cause interference with visual memory.

Limiting the use of verbal coding in the Visual Patterns Test

The aims of the study were to assess the availability of verbal coding and its effect on performance in a standard visual matrix task, the Visual Patterns Test (VPT). In a pilot study, participants were presented with the patterns from the VPT and were asked to name the shapes within them. Availability of verbal codes was low overall; however, some patterns resulted in a higher mean number of labels than others. A modified version of the test was created from those patterns that had produced the lowest mean number of labels. A total of 60 participants then took part in an experimental study, which was carried out to assess whether or not the availability of verbal coding affects task performance. It was found that the modified version resulted in a lower visual working-memory span than that of another version in which the availability of verbal coding was higher. The study confirmed that verbal coding does influence visual matrix task performance; however, the modified version now offers a selection of patterns from the VPT where verbal coding has been limited.

Cognitive Mechanisms of Visual Memories and Visual Images

Two experiments are reported that investigate recent claims that a visual memory and a visual image access different mechanisms within working memory and are differentially susceptible to interference. Experiment 1 demonstrates that when participants are required to hold the visual memory in consciousness, the representation is liable to interference in the same way as a visual image. Experiment 2 strengthens this interpretation by showing that the interference is specifically visual rather than general. Additionally, the experiments argue that visual noise interference is front loaded and does not require access to long-term memory structures prior to causing disruption.