Mid-shelf Shopper bias…?

In their article 'Preferring the One in the Middle: Further Evidence for the Centre-stage Effect',  researchers Paul Rodway, Astrid Schepman and Jordana Lambert of the University of Chester, UK analyse three separate but related experiments in which they tested the association between the location of an item in a series and how often that item is selected as preferable over other choices. The results indicate a clear tendency toward favouring items located in the middle of a row -- regardless of whether it runs horizontally or vertically. (access study )

"People may not be aware of this preference, but it may influence choice in a wide range of day-to-day settings, such as the products people buy in shops or via online shopping, the responses they provide in surveys, and potentially the people they select for a range of tasks or functions," Rodway said.

In the final test, researchers attempt to generalise the results of previous experiments. Instead of presenting pictures on a questionnaire, they asked participants to choose among a display of actual pairs of socks. Half of those surveyed viewed the column of socks at head level and the remainder observed it at thigh height. Once again the results supported the so called 'center-stage effect'. Most participants chose the middle pair of socks -- though researchers noted that pairs in the lowest two locations on the display were chosen least often -- a result that could indicate a relationship between the relative height of an item on display and consumer preference.

Or perhaps even relative heights of shoppers?