In conjunction search, response latencies usually increase with the number of displayed elements, suggesting serial, self-terminating search through all elements. In line with the results of H. Egeth, R. Virzi, and H. Garbart (1984), the present study shows that subjects do not necessarily search all display elements, but can limit their search to a color-defined subset of elements. The results make clear that selective search for a color-defined subset does not depend on saliency of the subset (Experiment 1), that selective search can be purely color-based and does not depend on luminance (Experiment 2), and that subjects can flexibly change which subset they are searching (Experiment 3). Experiment 4 showed that subsetselective search also occurs without fast absent responses as found in Experiments 1-3 and that for selective search no explicit instruction is required. Subset-selective search is a likely strategy in conjunction search.

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The validity of driving simulators for behavioral research is discussed. The concept of validity is introduced and explained, and a survey of validation studies follows, in the TNO driving simulator and others, comparing field and simulator study results. Results for mid-level driving simulators show that generally absolute validity of route choice behavior is obtained and relative validity of speed and lateral control behavior is obtained. There is evidence suggesting that for a number of applications the presence of a moving base and possibly a higher image resolution might increase the validity of a driving simulator.

With this paper we take a first step to understand the appropriation of social media by the police. For this purpose we analyzed the Twitter communication by the London Metropolitan Police (MET) and the Greater Manchester Police (GMP) during the riots in August 2011. The systematic comparison of tweets demonstrates that the two forces developed very different practices for using Twitter. While MET followed an instrumental approach in their communication, in which the police aimed to remain in a controlled position and keep a distance to the general public, GMP developed an expressive approach, in which the police actively decreased the distance to the citizens. In workshops and interviews, we asked the police officers about their perspectives, which confirmed the identified practices. Our study discusses benefits and risks of the two approaches and the potential impact of social media on the evolution of the role of police in society.