Day and Schoemaker (both The Wharton School) urge managers to be aware of events emerging on the periphery of their businesses, which often indicate important hidden opportunities and potential threats. They present a "strategic eye exam" to diagnose a company's peripheral vision and then describe a five-step process for improving vigilance. Illustrative case studies include Anheuser-Busch's anticipation of low-carb beers and Mattel's failure to recognize the potential impact of Bratz dolls on the Barbie dynasty. Annotation ©2006 Book News, Inc., Portland, OR (booknews.com)