title: The detection of feature singletons defined in two dimensions is based on salience summation, rather than on serial exhaustive or interactive race architectures.
abstract: Influential models of visual search assume that dimension-specific feature contrast signals are summed into a master saliency map in a coactive fashion. The main source of evidence for coactivation models, and against parallel race models, is violations of the race model inequality (RMI; Miller, 1982) by redundantly defined singleton feature targets. However, RMI violations do not rule out serial exhaustive (Townsend & Nozawa, 1997) or interactive race (Mordkoff & Yantis, 1991) architectures. These alternatives were tested in two experiments. In Experiment 1, we used a double-factorial design with singleton targets defined in two dimensions and at two levels of intensity, to distinguish between serial versus parallel models and self-terminating versus exhaustive stopping rules. In Experiment 2, we manipulated contingency benefits that are expected to affect the magnitude of redundancy gains and/or RMI violations on the assumption of an interactive race. The results of both experiments revealed redundancy gains as well as violations of the RMI, but the data pattern excluded serial-exhaustive and interactive race models as possible explanations for RMI violations. This result supports saliency summation (coactivation) models of search for singleton feature targets.
authors.affiliation: Department of General Psychology, Ludwig-Maximilians-Universität München, Leopoldstr. 13, 80802 Munich, Germany. mzehetleitner@psy.lmu.de
authors.forename: Michael
authors.initials: M
authors.lastname: Zehetleitner
authors.forename: Joseph
authors.initials: J
authors.lastname: Krummenacher
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Müller
mesh_terms: D000328:Adult; D001288:Attention; D003118:Color Perception; D015350:Contrast Sensitivity; D003657:Decision Making; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009949:Orientation; D010364:Pattern Recognition, Visual; D011214:Practice, Psychological; D011601:Psychophysics; D011930:Reaction Time; D055815:Young Adult