How do visual features combine?

Color and shape are ubiquitous visual features in design. For example, to make a button easily distinguishable from its surroundings, we can change its color, shape, or both.

One thing we may want to know is, how do users use color and shape information to find the button?

What kind of benefit do we get when we use both color and shape features in our design, compared to using only one of them? 

How do color and shape information combine in human vision?

Step 1: quantify how color alone affects visual cognition

This is measured by how fast people find a target object among distractor objects when the two differ in color only. 

Step 2: quantify how shape alone affects visual cognition

Similarly, it is measured by how fast people find a target object among distractor objects when the two differ in shape only.

Step 3: quantify how color & shape together influence visual cognition

We developed different mathematical models for how, in theory, color and shape information might combine in human vision. 

Then we measured performance of finding the target among distractors when the two differ in both color and shape. 

Finally, we compared how well the different models predicted the observations. 

Computed the search efficiencies when only color information is available (Experiment 1) and when only shape information is available (Experiment 2).

Predicted search efficiency when both color and shape information is available and see how good it fit to the observed data in Experiment 3.  

When both color and shape information are available, people optimally combine and use both to speed up their performance.

So better to have both color and shape information available for users when designing your products!

This study was published on Scientific Reports, also presented as a poster at Vision Science Society 2018 Annual Meeting.

It was also presented in 2 seminar talks at Psychology Department at University of Illinois at Urbana-Champaign.

A follow-up study on how shape and texture information combine was conducted and presented as a poster at Vision Science Society 2020 Annual Meeting, and published on Scientific Reports.

Long story short: people utilize shape & texture information less efficiently compared to color & shape, but still it's better than having only shape or only texture dimension.

I am now working on expanding this study to objects defined by three visual properties (color, shape and texture). I am incorporating a Bayesian Probability approach in the computational modeling of the triple feature combinational search.