Retailers know that shelf placement has a big impact on sales. New research has shown in more detail how this works. A study co-authored by Onur Bodur of Concordia University's John Molson School of Business and researchers at HEC in France and the Aston Business School in England has found that the consumer's eyes have a central focus. Using infrared eye-tracking technology, the researchers monitored the eye movements of subjects as they scanned a shelf full of nondescript products of fictitious brands in various categories. The results showed the brand placed at the horizontal centre of each category was chosen most often, suggesting retailers should focus more attention on product adjacencies within categories in order to boost sales of particular brands. The researchers attributed the results to an unconscious human tendency to gather the most information from the centre of any given scene. Also, the eye tends to place the pupil at the centre of the field of vision, while other research has shown that the longer a subject focuses on a particular product, the more likely it is to be chosen.