PHILADELPHIA: The importance of product display is well-known to retailers, but new research suggests that, when faced with an assortment to pick from, consumers' choices can be imperceptibly swayed by whether the items are displayed vertically or horizontally.

A paper for the Journal of Marketing Research, A 'Wide' Variety: Effects of Horizontal Versus Vertical Display on Assortment Processing, Perceived Variety, and Choice, explored how horizontal versus vertical displays of alternatives affect assortment processing, perceived variety and subsequent choice.

One of the authors, Barbara Kahn, Professor of Marketing, The Wharton School, University of Pennsylvania, explained that "if you take the same number of items and array them horizontally or vertically it changes the perception of variety".

"It's a very subtle effect and it doesn't last for a long time," she added.

This is essentially a consequence of the nature of human vision. "When it's horizontal, since your eyes are horizontal – what we call binocular vision – you can take in the items in the assortment more easily. It's called higher perceptual fluency.

"And because it's just a little easier to take in the items when they're horizontal, you think there's more variety there," Kahn said.

"When it's vertical you can't take as much in at once, plus you tend to move your head a little bit which [makes it] just that much harder."

After only a few seconds the effect goes away, but since people generally don't think much about this the initial impression lingers.

"If you think there's more variety you tend to seek more variety in your choices. And when you seek more variety in your choices you tend to purchase more overall," Kahn said.

The finding has implications for retailers, both online and offline. "If you want people to choose more than one in a product category, then it might be better to array them horizontally," she suggested.

"But if you want people to choose the most preferred or be brand loyal to something then a vertical assortment might make more sense."

Khan also noted a trend in retail towards "curated assortment" in an attempt to make the plethora of choice simpler for customers.

"If you can learn some of these cues to make the variety seem less or more depending on what your goal is, you can still have big assortments," she concluded.

Data sourced from Journal of Marketing Research, Knowledge@Wharton; additional content by Warc staff