Research Insight | Consumers Perceive Star Ratings to Be Higher than Numerals
What seems higher: four-and-a-half stars on Yelp or a rating of 4.5 on Uber Eats? A Journal of Marketing Research study shows that our brains don’t interpret every rating format the same way: When we see partially filled stars, our brains can’t help but “complete” them (raising the perceived rating), while numeric ratings make us fixate on the leftmost digit, subtly pulling the rating down. The researchers quantified these biases, finding that fractional star ratings often appear about 0.12 points higher than they really are (so 3.5 might feel more like 3.62). In contrast, numeric fractions get pulled down by around 0.05 points, making 3.5 seem closer to 3.45. In other words, star ratings create a mild “rose-tinted glasses” effect, whereas numbers are slightly deflated.
To capitalize on this, marketers can use shapes like stars, circles, and bars to show product ratings, effectively boosting how consumers perceive products. At the same time, policymakers may want to consider standardizing rating formats to avoid such inflation of consumers’ expectations. The researchers show that by removing the obvious partial outlines—so the half star doesn’t look incomplete—people are less tempted to mentally “complete” the shape. The findings suggest this design tweak can rein in the tendency to overestimate star ratings, thereby presenting customers with an accurate picture.
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What You Need to Know
- Our brains tend to fill in missing shapes, making fractional star ratings seem higher than they actually are and presenting an opportunity for marketers to subtly influence consumer choices.
- Numeric ratings seem about 0.05 points lower due to our focus on the leftmost digit (e.g., 3.5 feels like 3.45), meaning a numeric format provides a more accurate reflection of the true rating.
- Presenting a fractional star as a filled-in portion of a whole, “visually complete” star negates both the overestimation and underestimation of the rating.
Abstract
Some retailers use stars while others use Arabic numerals to present product ratings. Do consumers evaluate product ratings differently depending on the format? Which format more accurately represents the true magnitude of ratings? Across 12 experiments, we find that neither format is veridical. Consumers overestimate fractional star ratings (e.g., 
) and underestimate fractional Arabic numerals (e.g., 3.5). The overestimation of graphical ratings arises from the visual-completion effect: When the visual system perceives an incomplete image of a star, it instinctively activates the complete image, causing consumers to anchor their magnitude judgments on rounded-up numbers (i.e., evaluation of 
is anchored on 
). Importantly, our results show that this overestimation of star ratings can be mitigated by using visually complete stars (e.g., 
). Conversely, the underestimation of Arabic numeral ratings stems from the left-digit effect, which leads consumers to anchor magnitude judgments on rounded-down numbers (i.e., evaluation of 3.5 is anchored on digit 3). Thus, both star and Arabic numeral ratings are systematically misestimated by consumers, with the extent of misestimation varying based on the fractional value and the star-filling technique employed. These findings demonstrate that prevalent rating formats are misleading, highlighting the need for new industry standards.
Deepak Sirwani, Srishti Kumar, and Manoj Thomas, “Overestimating Stars, Underestimating Numbers: The Hidden Impact of Rating Formats,” Journal of Marketing Research, 62 (5), 937–57. doi:10.1177/00222437251322425.