Key Findings
- There is a counterintuitive relationship between perceptual noise and confidence for perceptual judgments, such that the more noise can sometimes lead to greater confidence.
- Specific areas of the prefrontal cortex located on a posterior-to-anterior axis are implicated in the control of increasingly complex components of perceptual decision making.
- Understanding the processes that contribute to confidence in visual perception is a long-term goal of the field.
At the heart of science exists a drive to explore the mysterious—to assess it, to classify it, and to understand it. While this drive is in no way new, modern technology has made it possible to access the innermost mystery: the human brain. Indeed, many fundamental neural components of sensory perception remain only partially understood. Thanks to the invaluable contributions of Dr. Dobromir Rahnev, we are growing closer to understanding how individuals process environmental stimuli to form subjective perception. For his endeavors in this area, as well as his ongoing dedication to collaborative research, FABBS is delighted to award Dr. Rahnev an Early Career Impact Award, as nominated by the Psychonomic Society.
Born and raised in Bulgaria, Dr. Rahnev’s use of advanced computational modelling was foreshadowed by a love of mathematics. As a child and adolescent, he competed in mathematics competitions, earning two gold medals from the International Mathematical Olympiad before beginning his undergraduate studies at Harvard University. After enrolling in courses on psychology, Dr. Rahnev’s zeal for mathematics transformed into a passion for psychological research. It was not until earning a Ph.D. from Colombia University, that he found himself at home in a lab that researched the subjective aspects of visual perception.
“Whether consciously or unconsciously…some part of your brain is making decisions about the most likely interpretation of what is in front of you.”
Dr. Dobromir (Doby) Rahnev
Dr. Rahnev is an associate professor of psychology at Georgia Tech. He is the primary investigator of the Perception, Neuroimaging, and Modeling (PNM) Lab (http://rahnevlab.gatech.edu) where his team uses technologies like fMRI and transcranial magnetic stimulation (TMS) to explore questions of perceptual decision making, with an emphasis on aspects of visual metacognition. In a recent interview with FABBS, Dr. Rahnev discussed the current directions and potential implications of his research, as well as the path that led him to this point.
Dr. Rahnev recalls, “Previously, I thought that vision is the most boring thing. What is there about vision? Just open your eyes and see! But then I started to realize that it’s super interesting… and there’s so many [things] you can do.” During his graduate studies, Dr. Rahnev became familiar with techniques like fMRI and TMS, and his work in visual metacognition (what people think about their own visual perceptions) revealed a counterintuitive pattern: in some cases, adding noise to a visual stimulus makes participants more confident in their assessment of the stimulus.
“When visual information is not perfectly clear—it’s ambiguous, it’s degraded—we need to go through a process of decision making to make a judgement about what’s in front of us. It can be conscious, or unconscious.”
As an associate professor at Georgia Tech, Dr. Rahnev’s work has focused on addressing the processes by which this visual decision making happens and combines multiple methodologies to better pinpoint the neural regions implicated in these processes.
His work has offered insight on how areas within the prefrontal cortex are linked with specific aspects of perceptual decision making. In addition to strengthening our general understanding of neural processing, these findings may be useful in medical contexts, or help experts understand the limits of visual perception in legal settings (ex: eyewitness testimony). Moving forward, Dr. Rahnev aims to expand on these questions by exploring how vision may be influenced by other sensory input, how disease may influence perceptual decision making, and how these processes may operate using technologies like virtual reality.
In addition to these accomplishments, Dr. Rahnev has displayed a strong dedication to collaborative research efforts. In 2022, he spearheaded a publication which outlined the collective medium- and long-term goals for visual metacognition researchers, which incorporated input from 26 researchers in the field. He also oversaw the creation of the Confidence Database, a field-wide repository for data regarding confidence ratings. Currently, the Confidence Database hosts data from 18 countries across the world, with over 8,700 participants and nearly 4 million trials.
Future Directions
- The use of multiple methodologies simultaneously (for example, fMRI in tandem with TMS) can help achieve a more wholistic understanding of perception processes.
- Pinpointing specific neural regions associated with perceptual decision making can inform medical treatments.
- Understanding how confident individuals feel in their interpretations of ambiguous visual stimuli may be useful in legal settings (ex: eyewitness testimony).
Dr. Dobromir (Doby) Rahnev is a recipient of the 2023 Federation of Associations in Behavioral & Brain Sciences (FABBS) Early Career Impact Award and was nominated by The Psychonomic Society.
The Psychonomic Society’s 64th Annual Meeting takes place on November 16-19, 2023, in San Francisco, California, USA.
Read more about Dr. Rahnev’s work at the links below:
