Eye movements during visual search for artistically embedded targets

Abstract

Eye movements were measured as subjects searched for a word target embedded in line drawings. Time taken to find the target was directly related to the degree of embeddedness or target conspicuity. Detections were predicted by multiple-fixation clusters exceeding 400 msec within 3 deg of the target. Search errors resulted from faulty pattern recognition in which the target was fixated, but for dwell times shorter than the 400-msec detection threshold found for hits. Dwell time is taken to reflect recognition and decision processes used to discriminate real from potential targets. Several search tasks have shown that the conspicuity of the target, defined as the degree to which the target is embedded in the surround, directly influences target detection (Kundel & Nodine, 1978; Kundel, Revesz, & Graber, 1974). Embedded targets, because they have more features in common with the surround and there­ fore blend into it, are harder to find than nonembedded targets that stand out from the surround. targets (the word NINA) in artist Al Hirschfeld's drawings, are noted for their lack of conspicuity because most of the features of the word are constructed of the same lines used to make up the picture. Finding NINAs is both entertaining and instructive, because it shows how the artist effectively uses the principle of embed­ ding to hide targets in an artistically rendered scene. In fact, and paradoxically, the background in which NINAs are embedded is usally considered the fore­ ground from both the artist's and the viewer's point of view, and the NINA targets are synonymous with Hirschfeld's signature. Other artists have also experi­ mented with the principle of embedding to hide figures in their art works. One of the best known examples is Salvador Dali's painting, The Slave Market with Disappearing Bust of Voltaire. From these examples, it is clear that the artist has discovered that the principle of embedding depends on the interrelationship between target and background. greater the overlap between these two feature sets, the greater the degree of embedding. In a similar way, military targets are embedded in scenic backgrounds using another invention of the artist: camouflage. In this case, the principle of embed­ ding may include not only overlap of target and back