Picture two grocery aisles stocked with the exact same five yogurt flavors. In one, the containers are pushed snugly together. In the other, they’re spread out with noticeable gaps between each one. Would you actually buy differently depending on which aisle you walked down?
According to a paper published in Marketing Letters, the answer is yes. Shoppers facing closely spaced products tend to pick a wider mix of items than shoppers looking at the same products spread farther apart. The research points to a shift in how buyers pay attention as the reason behind the pattern.
The question behind the research
Retailers have long known that where products sit on a shelf influences what gets purchased. Prior work has shown that placing an item next to something appealing makes it more attractive, and that surrounding empty space can change perceptions of a product’s size. What had received less attention is whether the gaps between items in a single assortment change the mix of items a shopper chooses.
Jung Min Jang of Brunel Business School, along with Song Oh Yoon and Cecile K. Cho of Korea University, set out to test this. Their starting idea draws on research in visual perception showing that when items sit close together, the brain tends to process them as a group. When items are separated by space, the brain picks out individual features instead. The team reasoned that this difference in visual processing might cascade into how certain shoppers feel about their preferences, and ultimately into what ends up in the basket.
Testing the hunch with chocolate, juice, snacks, and pens
The team ran five experiments across four product categories, each giving participants the chance to pick multiple items from a small assortment.
In the first study, 104 undergraduates were offered six free chocolate bars of their choice from four Cadbury flavors arranged on a plate. For half the participants, the bars sat flush against each other. For the others, two-inch gaps separated them. Those who chose from the tightly packed plate ended up picking a wider variety of flavors than those choosing from the spread-out plate.
The second study moved the setup online. Roughly 300 participants recruited through Prolific imagined shopping on a juice retailer’s website and picked six juices from four flavors. The juices were displayed with no gap, a one-inch gap, or a two-inch gap. Variety-seeking was higher in both the no-gap and the moderate-gap conditions compared with the wide condition, though it didn’t differ much between no-gap and moderate. This hints that once spacing drops below some threshold, making products even closer doesn’t push variety-seeking any further.
The researchers also checked whether other plausible explanations might account for the effect. Did closely packed displays make people feel cramped or more engaged, or make the assortment feel more like a unified group? None of these subjective measures differed across spacing conditions.
A memory test for attention
To see whether attention really was doing the work, the team tried a different approach in the third study. Participants viewed four foreign snacks on a computer screen, either tightly grouped or spaced apart, and picked up to six to take home. After a 20-minute unrelated task, they were given two surprise memory tests.
One test asked them to identify each snack’s specific name and flavor. The other asked them to place shuffled snack images back in their original order on the screen.
The results split along spacing lines. Participants who’d seen the widely spaced snacks were better at recalling the individual product details. Participants who’d seen the closely spaced snacks were better at reconstructing the overall arrangement. The two groups seemed to have encoded different kinds of information, matching the idea that spacing nudges attention toward either individual items or the group as a whole.
How preferences become fuzzier
The fourth experiment tested the next link in the chain: whether this attentional shift actually makes preferences less defined. The researchers gave 107 undergraduates the juice-shopping task again, but this time half of them rated each juice before picking, and half picked first and rated afterward.
When people chose first, the familiar pattern appeared. Close spacing led to more variety-seeking, ratings varied less across the options (suggesting fuzzier preferences), and the ratings people gave afterward were a weaker predictor of what they had actually picked. But when people rated each juice individually before choosing, the spacing effect vanished. Forcing attention onto each product one at a time seemed to override whatever the layout was doing.
A statistical analysis tied these pieces together: the variance in product ratings (a stand-in for how distinct someone’s preferences were) explained the link between spacing and variety-seeking, but only in the choice-first condition.
Familiarity changes the picture
The final study used real money. Students received $10 and could spend any portion of it on highlighter pens in five colors, priced at $1 each. The pens sat either in a tight row or with two-inch gaps.
Among participants who weren’t familiar with the brand, the close-spacing group bought more colors on average (3.14 versus 2.36) and more pens overall (about 5.95 versus 3.72). Among participants who already knew the brand well, spacing made no meaningful difference to either measure. The researchers interpret this as consistent with their broader story: when someone already has well-formed preferences about a product, a tight or loose display doesn’t change what they want.
What it means for shoppers and stores
The authors suggest a few practical takeaways. For shoppers trying to rein in impulse variety-buying, evaluating options one at a time rather than scanning the whole shelf may help keep preferences clearer and baskets smaller.
For retailers, the research suggests spacing is a lever that can be pulled. Tighter displays could nudge customers toward sampling a broader range of flavors or trying unfamiliar items. Wider displays could support shoppers in zeroing in on a favorite, which might matter more for established brands hoping for repeat purchases. The authors note this plays out differently across store formats, since supermarkets often give each brand substantial horizontal shelf real estate, while convenience stores pack brands in more tightly.
Caveats
The authors flag several limits. Their evidence for the attention-and-certainty mechanism is indirect, and overlapping explanations such as processing fluency or cognitive load haven’t been ruled out. They also can’t pin down the precise point at which spacing starts or stops mattering, which likely depends on product size and viewing distance. Eye-tracking and other direct measures of attention would allow sharper tests. The spacing manipulations in these studies were also modest (two inches at most), so it’s unclear how the effect scales in physical stores with larger displays.
