Much is known about attentional switching across space, but much less about switches between nonspatial domains such as category or task. Nonetheless, extensive information about attentional switching in both spatial and nonspatial domains can be found in the experimental literature on a phenomenon known as the attentional blink, in which a switch is required between 2 rapidly sequential targets. If the 2 targets follow one another directly, identification of the second target is almost perfect when no attentional switch is required between the targets or when the switch is unidimensional. In contrast, identification is impaired with switches in location or with multidimensional switches. This pattern of results is consistent with the joint operation of location-specific endogenously controlled input filters and exogenously controlled domain-specific modules. Attentional Switching in Spatial and Nonspatial DomainsAttention can be distributed across space or among nonspatial stimulus attributes such as color, shape, or category. Distribution of attention across space has been studied extensively (see reviews by Kinchla, 1992, & LaBerge, 1990. A major objective of those studies was to discover the rules that govern how quickly, how accurately, and under what conditions the focus of attention can be switched to different regions in space. In contrast, as was pointed out by Allport, Styles, and Hsieh (1994), the study of attentional set in domains other than spatial has been aimed principally at discovering how well a given set can be maintained in the presence of interfering stimuli. Well-known examples are studies of the Stroop effect (reviewed by MacLeod, 1991) and of dual-task interference (reviewed by Pashler, 1998, especially chapter 6). Considerably less work has been done on the dynamics of switching attentional set in nonspatial domains.In studying the dynamics of attentional switching, whether in spatial or nonspatial domains, the main issue is how the cognitive system reconfigures itself to cope with rapidly changing demands

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We assessed the role of saliency in driving observers to fixate the eyes in social scenes. Saliency maps (Itti & Koch, 2000) were computed for the scenes from three previous studies. Saliency provided a poor account of the data. The saliency values for the first-fixated locations were extremely low and no greater than what would be expected by chance. In addition, the saliency values for the eye regions were low. Furthermore, whereas saliency was no better at predicting early saccades than late saccades, the average latency to fixate social areas of the scene (e.g., the eyes) was very fast (within 200 ms). Thus, visual saliency does not account for observers' bias to select the eyes within complex social scenes, nor does it account for fixation behavior in general. Instead, it appears that observers' fixations are driven largely by their default interest in social information.

The present study examined how social attention is influenced by social content and the presence of items that are available for attention. We monitored observers' eye movements while they freely viewed real-world social scenes containing either 1 or 3 people situated among a variety of objects. Building from the work of Yarbus (1965/1967) we hypothesized that observers would demonstrate a preferential bias to fixate the eyes of the people in the scene, although other items would also receive attention. In addition, we hypothesized that fixations to the eyes would increase as the social content (i.e., number of people) increased. Both hypotheses were supported by the data, and we also found that the level of activity in the scene influenced attention to eyes when social content was high. The present results provide support for the notion that the eyes are selected by others in order to extract social information. Our study also suggests a simple and surreptitious methodology for studying social attention to real-world stimuli in a range of populations, such as those with autism spectrum disorders.

Recurrence quantification analysis (RQA) has been successfully used for describing dynamic systems that are too complex to be characterized adequately by standard methods in time series analysis. More recently, RQA has been used for analyzing the coordination of gaze patterns between cooperating individuals. Here, we extend RQA to the characterization of fixation sequences, and we show that the global and local temporal characteristics of fixation sequences can be captured by a small number of RQA measures that have a clear interpretation in this context. We applied RQA to the analysis of a study in which observers looked at different scenes under natural or gazecontingent viewing conditions, and we found large differences in the RQA measures between the viewing conditions, indicating that RQA is a powerful new tool for the analysis of the temporal patterns of eye movement behavior.