Dynamic visual noise: No interference with visual short‐term memory or the construction of visual images

Abstract

The effects of dynamic visual noise (DVN) and static visual noise (SVN) were assessed on a visual short‐term memory (STM) task, in which a matrix pattern was briefly presented and followed by a recognition test, and a new, cumulative imagery task, in which the elements of a pattern were presented one at a time, and participants were asked to imagine the pattern formed by displaying all the elements together. When presented during the retention interval neither DVN nor SVN affected visual STM performance. The cumulative imagery task was not affected by visual noise presented either during the retention interval or concurrently while the elements of the pattern were shown. Increasing the spatial demands of the task decreased performance, but did not interact with type of visual noise. The results (1) show that DVN in relatively short bursts does not interfere with visual STM, (2) argue against the view that DVN impairs the localisation of pattern elements, and (3) provide no support for the view that concurrent DVN mandatorily disrupts the formation of visual images. The implications for studies of visual imagery and visual STM are discussed.

Notes

Correspondence should be addressed to S. E. Avons, Department of Psychology, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK. Email: [email protected]

Because the pegword is a mnemonic task, effective at creating durable memory representations, we will assume here that images are not maintained continuously until the test. In any case the capacity limitations of visual imagery make this unlikely, since a number of conjoint images would need to be maintained simultaneously. In accord with this assumption, Zimmer and Speiser (2002, Exp. 4) reported no interference of an attended secondary task presented during the retention interval of the pegword task.

One concern is that the representations formed in the cumulative imagery task may be stable and resistant to decay or any kind of interference. To test this we conducted an informal experiment in which participants had to make a decision using visual STM between the presentation of pattern elements and the cumulative imagery test. To do this, a 0.5 s target pattern made of slanting line segments followed the final element of the cumulative imagery probe, and this was followed by a 2 s delay and then a 0.5 s test pattern. Participants responded if the target and test patterns were the same, and then responded to the cumulative imagery test. This procedure showed a clear decrease in performance relative to the case where cumulative imagery was tested after a 3 s retention interval. Although not conclusive with respect to the causes of the decrease, this showed that the cumulative imagery representation was not stable and was consistent with the sensitivity to interference shown in visual STM studies.