Altering Lines and Contours in a Picture Can Increase Likeability

a city street at sunset

We’ve all had the sensation of staring at a photograph — of a sunset, a person, a stylish vehicle, or a cute animal — and finding it quite appealing. But why? Are we culturally conditioned to enjoy certain visuals over others, or is there anything more going on in our brains?

One of the main goals of Dirk Bernhardt-Walther’s lab, an associate professor in the University of Toronto’s Faculty of Arts & Science’s psychology department, is to comprehend the psychological processes that underpin aesthetic perceptions.

New work co-authored by Bernhardt-Walther and Ph.D. student Delaram Farzanfar demonstrates that simply changing a scene’s lines and contours can boost its likeability.

Predicting Visual Appeal

In the study, the researchers asked 75 participants to rate how much they liked line drawings of complex scenes. The researchers then derived a statistical model of the importance of contour properties — such as orientations, curvature, junctions and symmetry — to measure the aesthetic appeal of the drawings.

t-junction image
Line drawing analyses from Experiment 2. Credit: Psychological Science (2023). DOI: 10.1177/09567976231190546

By selectively removing contours based on their predicted appeal, Farzanfar and Bernhardt-Walther generated two versions of each drawing. One was predicted to be liked more than the other.

As predicted by the statistical model, when a fresh group of 77 participants saw these altered drawings, they did, in fact, favor one version over the other—despite the fact that both drawings showed the same scene.

“These are the properties that we measured and manipulated. We show that by selecting certain contours in an image based on these properties, we can make people like an image more or less.”

said Bernhardt-Walther.

T Junction Aesthetics

Other studies have been conducted on aesthetic valuation of images. But Bernhardt-Walther says these studies examined images as a whole—not the shapes or spatial relationships contained within them.

“We think that’s important,” he said. “We developed these algorithms to measure contour properties, and we can use these algorithms in other studies. Our lab made a major effort during the pandemic to develop these techniques to measure contour properties that could not be measured automatically before.”

The set of algorithms, known collectively as the Mid-Level Vision Toolbox, was able to predict, and then confirm, that structural regularities in an image increase the likelihood that people will find it pleasing. In particular, the presence of “T junctions” in a scene—the effect created when a horizontal line is placed atop a vertical one—elevates a picture’s likeability.

The researchers believe that regularity in the way lines and shapes appear in a picture may elicit a sense of psychological safety in the viewer; arrangements that are more familiar, and that make geometric sense to viewers, may thus appear to be more likable.

Perceptual Reward System

The findings are consistent with the idea of a perceptual reward system. Most likely, the visual qualities that provided evolutionary advantages are what make aesthetic pleasure possible.

Interestingly, the team discovered that aesthetic ratings of nature sceneries were lower when line drawings were reviewed than when photos were evaluated. Line drawings of cities and other man-made objects, on the other hand, were preferred above their photographed counterparts.

Marketers, designers, architects and others all stand to benefit from studies such as this, which help to increase our scientific understanding of aesthetic preference.

“The scientific study of aesthetics can help us develop evidence-based interventions for improved subjective well-being and social connectedness,”

said Farzanfar, who is also a registered psychotherapist. Farzanfar and Norman Farb, an associate professor of psychology at U of T Mississauga, are carrying out follow-up research in this area of study.

Bernhardt-Walther’s lab focuses on the neurological and computational concepts that underpin high-level sensory perception, but they are also making significant contributions to the discovery of an emergent aesthetic language. Bernhardt-Walther’s experience as a physicist, computer scientist, and psychologist puts him in a good position to ensure that new discoveries are technically solid.


To what extent do aesthetic experiences arise from the human ability to perceive and extract meaning from visual features? Ordinary scenes, such as a beach sunset, can elicit a sense of beauty in most observers. Although it appears that aesthetic responses can be shared among humans, little is known about the cognitive mechanisms that underlie this phenomenon. We developed a contour model of aesthetics that assigns values to visual properties in scenes, allowing us to predict aesthetic responses in adults from around the world. Through a series of experiments, we manipulate contours to increase or decrease aesthetic value while preserving scene semantic identity. Contour manipulations directly shift subjective aesthetic judgments. This provides the first experimental evidence for a causal relationship between contour properties and aesthetic valuation. Our findings support the notion that visual regularities underlie the human capacity to derive pleasure from visual information.

  1. Farzanfar, D., & Walther, D. B. (2023). Changing What You Like: Modifying Contour Properties Shifts Aesthetic Valuations of Scenes. Psychological Science, 34(10), 1101-1120. Doi: 10.1177/09567976231190546