The Shape of Threat: Simple Geometric Forms Evoke Rapid and Sustained Capture of Attention Christine L. Larson, Joel Aronoff, and Jeffrey J. Stearns Michigan State University Previous work has indicated that simple geometric shapes underlying facial expressions are capable of conveying emotional meaning. Specifically, a series of studies found that a simple shape, a downward- pointing “V,” which is similar to the geometric configuration of the face in angry expressions, is perceived as threatening. A parallel line of research has determined that threatening stimuli more readily capture attention. In five experiments, the authors sought to determine whether this preferential process- ing was also present for the simple geometric form of a downward-pointing “V.” Using a visual search paradigm, across these experiments the authors found that, when embedded in a field of other shapes, downward-pointing V’s were detected faster and, in some cases, more accurately than identical shapes pointing upward. These findings indicate that the meaning of threat can be conveyed rapidly with minimal stimulus detail. In addition, in some cases, during trials of homogeneous fields of stimuli, fields of downward-pointing V’s led to slower response times, suggesting that this shape’s ability to capture attention may also extend to difficulty in disengaging attention as well. Keywords: emotion perception, visual search, attentional bias, speeded detection, threat Major programs of research (cf. Ekman, 1973, 2003) provide substantial evidence to support Darwin’s (1872/1998) proposal that facial displays of emotion are expressed in similar ways in all cultures. This universality suggests that the sign vehicles that Ekman (1982) identified in the facial display of an emotion are served by a parallel set of innate feature detectors that facilitate the rapid recognition of the facial expression. This hypothesized set of feature detectors Ekman (2003) termed the “autoappraiser,” a term that directs our attention to those sets of innate appraisal mechanisms that permit observers to decode an emotional display. To further clarify our understanding of the stimuli that such “appraisers” might be designed to identify, a set of studies (cf. Aronoff, 2006; Aronoff, Barclay, & Stevenson, 1988; Aronoff, Woike, & Hyman, 1992) examined the sign vehicles that attract attention to a display of anger, reasoning that it would be an evolutionary benefit for the observer to recognize quickly such threats from another (Hansen & Hansen, 1994; Lundqvist & O ¨ hman, 2005). A set of naturalistic and experimental studies (Aronoff et al., 1988; Aronoff et al., 1992) sought to identify the elementary features in facial expressions that convey threat or happiness (as a contrasting visual image) as measured by their effects on a set of subjective semantic differential scales (Osgood, Suci, & Tannenbaum, 1957) that indicate the degree of “badness,” “potency,” and “activity” of each visual stimulus examined. These studies found that angular V-shaped images (similar to the angles in the eyebrows, cheeks, chin, and jaw in angry expressions) and rounded images (similar to the curves found in the cheeks, eyes, and mouth in happy expressions) conveyed an angry and a happy meaning, respectively (Aronoff, 2006; Aronoff et al., 1988, 1992). In fact, these studies provide evidence that simple nonrepresentational lines presented in different orientations and combinations, as well as large-scale static and dynamic configural shapes made by the whole body, provide the same information as do displays of specific facial features. These results, which focused on the configural stimuli formed by the movement of the face as a whole rather than the shape of single sign vehicles, are supported by Bassili’s (1978, 1979) pioneering studies, which showed that an emotional facial display creates a larger geometric form. Bassili placed luminescent dots on people’s faces in a dark room and asked them to assume first an angry and then a happy expression. In the happy display, a burst of points of light expanded outward to form a rounded shape, while in the angry display the points of light imploded downward and inward to form a V-shaped angle. Additional data, using schematic faces, further confirmed that V-shaped images are perceived as being more negative (Lundqvist, Esteves, & O ¨ hman, 1999), even when presented without any other facial features (Lundqvist, Esteves, & O ¨ hman, 2004). More recent work further indicates that images containing sharp angles, including both real and abstract objects, are perceived as less preferable than comparison curved objects (Bar & Neta, 2006). Thus, a substantial set of studies provides evidence that nonrepresentational geometric shapes are appraised as conveying the emotional meaning of anger and happiness. Furthermore, separate lines of research indicate that stimuli that signal potential threat, including angry faces, more readily capture attention (for review see Mogg & Bradley, 1999; Williams, Watts, MacLeod, & Mathews, 1997). The existence of simple, easily detectable representations of potential threat is consistent with Darwin’s (1872/1998) suggestion that speedy detection of threat confers an evolutionary advantage (cf. Niedenthal & Kitayama, 1994). Numerous studies have found facilitated detection of threat- related, compared with neutral and, in some cases, pleasant stimuli Christine L. Larson, Joel Aronoff, and Jeffrey J. Stearns, Department of Psychology, Michigan State University. Correspondence concerning this article should be addressed to Christine L. Larson, Department of Psychology, Michigan State University, 105B Psychology Building, East Lansing, MI 48824-1116. E-mail: larson37@msu.edu Emotion Copyright 2007 by the American Psychological Association 2007, Vol. 7, No. 3, 526 –534 1528-3542/07/$12.00 DOI: 10.1037/1528-3542.7.3.526 526