Spatial working memory predicts re-cancellation behaviour in neglect

The lateralised bias of spatial neglect can be modulated by concurrent non-lateralised impairments. For instance, people with left neglect may have spatial working memory deficits that prevent them from keeping track of locations visited in visual search tasks such as target cancellation. Not only do they omit targets in some parts of the array but they may revisit and re-cancel targets in other parts, and this re-cancellation behaviour increases dramatically in 'invisible' conditions, in which touching a target leaves no visible trace. It has been proposed that spatial memory deficits are the main reason for the rise of re-cancellation errors in invisible cancellation conditions. This idea predicts that spatial memory abilities should correlate with re-cancellation behaviour; but this expected relationship has never been demonstrated. The present study takes an exploratory approach to describing the behaviour of 18 people with left visual neglect, following right hemisphere stroke, on touchscreen tests of spatial working memory and target cancellation. We show that people with neglect who are less able to remember locations in a spatial memory task tend to make more re-cancellation errors in invisible cancellation conditions. We also describe an apparent trade-off, in which some people with neglect make many more re-cancellation errors, whilst others make many more target omissions. We suggest that the influence of spatial memory deficits on invisible cancellation tasks can be more fully captured by considering both types of errors, rather than re-cancellations only.