Reading habits contribute to the effects of display direction on product choice.

It has been shown that people process assortment variety more efficiently in horizontal displays than in vertical displays, owing to human visual characteristics that favor the horizontal direction. Consequently, the number and variety of products chosen tends to increase when they are arranged horizontally. I show that this horizontal display advantage can be modulated by culture, especially writing and reading habits. When Japanese participants, who write and read text vertically as well as horizontally, chose products in horizontal and vertical displays, horizontal displays did not consistently increase the variety of products chosen. In other words, the horizontal display advantage was eliminated (Experiments 1A and 1B). However, when Japanese readers initially read horizontally, it led to a robust advantage for the horizontal display. Similarly, initial vertical reading resulted in a vertical display advantage (Experiments 2 and 3). These results suggest that horizontal displays are not always advantageous, and that optimal display direction for product choice is affected by reading habits.