Using the Hand to Open the Hidden Mind

News subtitle

Nearly 2,000 Scientists Worldwide Using Mouse-Tracking Software to Reveal the Unconscious


June 3, 2014

A Dartmouth researcher’s invention tracking simple hand movements – or rather computer mouse movements – is helping a rapidly growing number of scientists around the world to explore the unconscious mind and the invisible forces that control human behavior. The scientists’ findings suggest the hand has a mind of its own, with the trajectory of hand movement able to reveal hidden psychological processes not seen using traditional methods.

MouseTracker, a data collection and analysis software package developed by Dartmouth Professor Jon Freeman and his colleagues, measures computer mouse movements during psychological experiments, revealing how participants’ real-time hand movements are pulled toward various alternatives and how split-second decisions crystallize in the brain. In other words, MouseTracker provides a window into how people “make up their minds” and the relatively unconscious processes that may occur in split seconds – whether in forming snap judgments about people, making financial decisions or deciding what to eat.

The first mouse-tracking study was published by other researchers in 2005, and Freeman’s MouseTracker software expanded on and popularized the technique by making it easy to use, more comprehensive and available free to scientists. Since 2008, more than 1,750 researchers worldwide have used it in a growing range of experiments to, among other things, detect strokes and other cognitive impairments, reveal racial and cultural biases and predict obesity levels, political elections, hiring outcomes, financial decision-making and social inequities. These researchers have produced more than 30 peer-reviewed articles to show how language is processed, how memories are retrieved, how objects are visually recognized, how mathematical problems are computed and numbers represented, how the visual perception of a face is biased by stereotypes and how people make moral decisions: “Will you give seven meals to one starving child or give two meals each to three starving children?” Researchers using MouseTracker are writing up or have under review dozens more peer-reviewed articles.

Researchers are using MouseTracker for nearly all domains of study in psychology as well as in many other fields, such as marketing, economics and clinical science. For example, the software is being used to identify subtle impairments in stroke patients and determine which products will do best on the market. It is being used to examine whether the way individuals in specific countries or geographical regions respond to visual stimuli predicts those regions’ social inequities, such as gender or racial disparities.

In their own research, Freeman and his team most recently used MouseTracker to show that female politicians’ success can be predicted by their facial features, especially in conservative states where women with more feminine faces tend to do better at the ballot box. They showed that whether a female politician was going to win or lose a real-world election could be predicted in only 380 milliseconds after participants were exposed to her face. They have also used the software to show how social information is extracted from faces and how facial cues activate related stereotypes (e.g., masculine cues activate “aggressive”). Additionally, they have used the software to develop a computational theory about how the brain automatically uses facial cues to categorize and stereotype other people – whether we like it or not. For example, individuals swerved closer to a “black” response when categorizing a face surrounded by low-status attire (e.g., janitor suit) and swerved closer to a “white” response when categorizing a face surrounded by high-status attire (e.g., business suit). The results expose the unconscious impact of stereotypes and context on how a face is visually perceived, regardless of what the individual consciously indicated.

For 150 years, the “reaction time” – the time it takes for an individual to make a response – has served as the gold standard for measuring how thought processes work in split seconds. While this speaks to the outcome of thinking (e.g., how long did a thought process take?), MouseTracker works by opening up that single outcome into a dynamic process. By examining how a participant’s response trajectory (a hand movement) stabilizes on a specific response, and may be pulled toward other possible responses, researchers glean valuable information about the process, rather than the products, of thinking. Researchers have used MouseTracker to discover how a single thought, perception, decision, judgment or other type of psychological response arises over other possible alternatives with millisecond-level precision in timing.

Jon Freeman, assistant professor of Psychological & Brain Sciences at Dartmouth College and director of the Social Cognitive & Neural Sciences Lab, is available to comment at