What does visual suffix interference tell us about spatial location in working memory?. Allen, R., J., Castellà, J., Ueno, T., Hitch, G., J., Baddeley, A., D., & Allen, R., J.
What does visual suffix interference tell us about spatial location in working memory? [pdf]Paper  abstract   bibtex   
A visual object can be conceived of as comprising a number of features bound together by their joint spatial loca-tion. We investigate the question of whether the spatial loca-tion is automatically bound to the features or whether the two are separable, using a previously developed paradigm where-by memory is disrupted by a visual suffix. Participants were shown a sample array of four colored shapes, followed by a postcue indicating the target for recall. On randomly intermixed trials, a to-be-ignored suffix array consisting of two different colored shapes was presented between the sam-ple and the postcue. In a random half of suffix trials, one of the suffix items overlaid the location of the target. If location was automatically encoded, one might expect the colocation of target and suffix to differentially impair performance. We carried out three experiments, cuing for recall by spatial location (Experiment 1), color or shape (Experiment 2), or both randomly intermixed (Experiment 3). All three studies showed clear suffix effects, but the colocation of target and suffix was differentially disruptive only when a spatial cue was used. The results suggest that purely visual shape–color binding can be retained and accessed without requiring infor-mation about spatial location, even when task demands en-courage the encoding of location, consistent with the idea of an abstract and flexible visual working memory system. Studies of visual working memory typically involve presen-tation of an array or sequence of visual objects and their subsequent testing by recognition or cued recall. A good deal of research has focused on the process of binding features, such as color and shape, into perceived objects, a process that under typical conditions appears to be relatively automatic (e.g., Allen, Baddeley, & Hitch, 2006, 2014; Allen, Hitch, Mate, & Baddeley, 2012). Such objects are, of course, spatial-ly located, and the question arises as to whether location functions in the same way as other features, such that objects are automatically bound to the location at which they are presented. In addressing this issue, it is important to distinguish two separate ways in which spatial location might prove important. First of all, one should bear in mind that by definition, a visual object requires that the relevant features be at the same location at the same time; a patch of red beside a square is not the same as a red square. In addition to this defining effect of colocation, there is another aspect of spatial location that is important, characterized either in absolute terms, as the position of the object within a spatial field, or relatively, on the basis of its spatial relationship to other objects, regardless of absolute location. In order to store the latter information, it is not sufficient to note that the features of color and shape are colocated; it also should be noted where the resultant object is located either within the visual field or in relation to other objects. The question arises as to whether the spatial location of a stimulus is automatically encoded and maintained in the same way as the spatial colocation of color and shape that defines the object. Woodman, Vogel, and Luck (2012) studied this question in a series of change detection experiments in which the test items were presented in the same or a different location from

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