The Role of Fear-Relevant Stimuli in Visual Search: A Comparison of Phylogenetic and Ontogenetic Stimuli Tobias Brosch and Dinkar Sharma University of Kent It has been argued that phylogenetic fear-relevant stimuli elicit preattentive capture of attention. To distinguish between fear relevance and time of appearance in evolutionary history, the authors compare phylogenetic and ontogenetic fear-relevant and fear-irrelevant stimuli in a visual search task. The authors found no evidence for a special role of phylogenetic fear-relevant stimuli; it seems that fear relevance in general is more important than is the evolutionary age. The pattern of results indicates that attention toward threatening stimuli is mainly affected by a late component that prolongs the disengagement of attention. Fear signals danger and helps people become aware of possibly menacing situations. If confronted with a threat, one should quickly decide whether to attack or to withdraw. Fear serves to interrupt other ongoing behavior, so that people can use all of their resources to cope with the danger (Lang, Davis, & O ¨ hman, 2000). Apart from showing the relevance of the situation, fear might also draw the attention toward threats more quickly than would be the case without the emotion. O ¨ hman and his colleagues (O ¨ hman, Flykt, & Lundqvist, 2000; O ¨ hman & Mineka, 2001) have proposed a theoretical framework of an evolved module of fear and fear learning that is based on the concept of biological preparedness (Seligman, 1971). This module is thought to be a relatively independent behavioral, mental, and neural system specifically designed to solve adaptive problems arising from potentially life-threatening situations. It facilitates the perception of threatening stimuli and enables the organism to quickly learn associations involving stimuli that signal danger. The module thus helps the organism to effectively deal with threaten- ing stimuli and increases its chances of survival. The neural circuitry subserving the fear module is thought to be organized around the amygdala and includes a short latency pathway from the thalamus to the amygdala termed the low road (LeDoux, 1996). Whereas this pathway is related to the auditory modality, Morris and colleagues (Morris, O ¨ hman, & Dolan, 1999) propose a collicular-pulvinar-amygdalar pathway as a shortcut for visual information. Via this pathway, visual information with emotional content might directly reach the amygdala without being diverted to cortical areas. The role of this shortcut has been questioned because the neurons of the superior colliculus are unable to dis- criminate at high spatial-resolution rates and thus would be unable to compute more complex visual stimuli (Pessoa, Kastner, & Ungerleider, 2002). Although fear-relevant auditory stimuli can travel the low road, it seems more plausible that emotional, visual stimuli reach the amygdala via a cortical path that leads from the corpus geniculatum laterale to the visual cortex, then on to occipi- totemporal regions, the inferior temporal area, and finally the amygdala (Gazzaniga, Ivry, & Mangun, 2002). To back up his proposal of an evolved fear module, O ¨ hman and colleagues have taken into account results from classical condi- tioning paradigms (O ¨ hman, Eriksson, & Olofsson, 1975; O ¨ hman, Frederikson, Hugdahl, & Rimmo ¨, 1976), masking paradigms (O ¨ hman & Soares, 1993), and visual search tasks (O ¨ hman, Flykt, & Estevez, 2001; O ¨ hman, Lundqvist, & Esteves, 2001). They have argued that the special position of phylogenetic stimuli is demon- strated by observations such as resistance to extinction, noncon- scious processing in masking paradigms and preattentive or facil- itated processing in visual search tasks. However, in each of these studies the comparison of phylogenetic fear-relevant and fear- irrelevant stimuli confounded fear relevance and a factor that concerns the time of appearance in the evolutionary history. The effects observed with phylogenetic stimuli may have been due to ontogenetic, culturally fear-relevant factors rather than to evolu- tionary factors. Studies that have manipulated the evolutionary age of the stim- uli have generally reported no special status of phylogenetic com- pared with ontogenetic stimuli. For example, using the classical conditioning paradigm, Hugdahl and Johnsen (1989) observed faster extinction for slides of snakes and spiders than for slides of guns. Similarly, in a backward masking paradigm Flykt (1999) showed identical masking effects for phylogenetic and ontogenetic stimuli. Another line of evidence for the fear module consists of studies that use visual detection tasks. Most studies in this area focus on the distinction between parallel and serial search (see, e.g., Treis- man & Gelade, 1980; Treisman & Gormican, 1988). Some of the early work on visual search investigated the efficiency of detection of emotional faces (Hansen & Hansen, 1988; but see Purcell, Stewart, & Skov, 1996). More recently, further evidence has been reported to support the claim for a more efficient search for phylogenetic fear-relevant stimuli, namely schematic threatening faces (O ¨ hman, Lundqvist, & Estevez, 2001) and pictures of snakes Tobias Brosch and Dinkar Sharma, Department of Psychology, Univer- sity of Kent, Canterbury, United Kingdom. The authors thank John Bargh and Jan de Houwer for valuable advice on a draft of this article and William Sonnen for programming the experiment. Correspondence concerning this article should be addressed to Tobias Brosch, who is now at Department of Psychology, University of Trier, Trier 54286, Germany. E-mail: bros1303@uni-trier.de Emotion Copyright 2005 by the American Psychological Association 2005, Vol. 5, No. 3, 360 –364 1528-3542/05/$12.00 DOI: 10.1037/1528-3542.5.3.360 360