When evaluating a product, the way its rating is presented can significantly shape consumer perception. For instance, a 3.5 rating displayed as stars versus numerals can evoke different impressions, making a product seem better or worse than it is. Recent research from the Cornell SC Johnson College of Business reveals that this seemingly small design choice can influence how potential buyers interpret quality, sometimes transforming a 3.5 rating into a psychological 4 or a disappointing 3, depending on the format. This subtle but impactful difference underscores the power of visual cues in shaping our understanding of product value.

In six experiments, researchers found that consumers overestimate fractional star ratings while underestimating equivalent numeric scores. This discrepancy arises from how our brains process images versus numerals. The study, published on May 15 in the Journal of Marketing Research under “Overestimating Stars, Underestimating Numbers: The Hidden Impact of Rating Formats,” highlights this cognitive bias. According to first author Deepak Sirwani, now an assistant professor at the University of British Columbia, our minds tend to “complete” visual patterns like partially filled stars, creating a more optimistic rating interpretation. In contrast, when the exact value is communicated as a number, our focus shifts to the leftmost digit, making 3.5 feel more like a 3 than a 4.

This distinction is not merely a quirk of perception but a fundamental difference in cognitive processing. Manoj Thomas, a professor of management at Cornell, described this as a critical breakthrough in their research. He explained, “Our results suggest that the brain representations activated when you process stars are entirely different from those triggered by Arabic numerals. This realisation — that our brains process these formats differently — was a significant a-ha! moment.” The visual nature of stars seems to trigger a more holistic and optimistic assessment, while numerals prompt a more analytical and, often, more conservative judgment.

The researchers tested this effect through a range of scenarios. In one key study, 616 participants were randomly assigned to one of three groups, each exposed to different rating formats: stars, numerals, or a combination of both. They were asked to estimate the value of 17 fractional ratings, ranging from 1 to 5 in 0.25 increments, on a blank horizontal line. Consistently, participants perceived star ratings as being higher than their numeric equivalents, suggesting a widespread and reliable cognitive bias.

These findings have significant implications for businesses that rely on ratings to communicate product quality. Understanding the psychological effects of rating formats is crucial in an era when consumers rarely purchase without first checking reviews. Sirwani noted, “Most of us do not buy anything without checking its rating nowadays, and ratings have become as powerful a predictor of purchase as price, brand, or even recommendations from friends and family.” This means that companies might inadvertently overpromise and underdeliver if they rely heavily on star ratings, or conversely, they might sell their products short by sticking to purely numeric evaluations.

Given the clear evidence that rating formats can skew consumer perceptions, the researchers argue for reevaluating industry standards. Consistent and intuitive formats could reduce the risk of miscommunication and better align consumer expectations with reality, potentially boosting customer satisfaction and loyalty. As digital marketplaces continue to dominate the retail landscape, the need for accurate, psychologically sound rating systems has never been more pressing.

More information: Deepak Sirwani et al, Overestimating Stars, Underestimating Numbers: The Hidden Impact of Rating Formats, Journal of Marketing Research. DOI: 10.1177/00222437251322425

Journal information: Journal of Marketing Research Provided by Cornell University