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Posted by on Aug 9, 2014 in Featured, Free Will and Determinism, Science | 9 comments

Our brains judge a face’s trustworthiness, even when we can’t see it

This fascinating article is from ScienceDaily. It is something I have talked about before with friends, that you can tell so much about a person (or at least think you can) from a cursory look to the face. And, indeed, your brain is doing n awful lot of this non-conscious computation along those lines:

Our brains are able to judge the trustworthiness of a face even when we cannot consciously see it, a team of scientists has found. The researchers quickly showed the study’s subjects images of real faces as well as artificially generated faces whose trustworthiness cues could be manipulated (as shown above) while examining the subjects’ neurological responses. Credit: Image courtesy of the Journal of Neuroscience

Our brains are able to judge the trustworthiness of a face even when we cannot consciously see it, a team of scientists has found. Their findings, which appear in the Journal of Neuroscience, shed new light on how we form snap judgments of others.

“Our findings suggest that the brain automatically responds to a face’s trustworthiness before it is even consciously perceived,” explains Jonathan Freeman, an assistant professor in New York University’s Department of Psychology and the study’s senior author.

“The results are consistent with an extensive body of research suggesting that we form spontaneous judgments of other people that can be largely outside awareness,” adds Freeman, who conducted the study as a faculty member at Dartmouth College.

The study’s other authors included Ryan Stolier, an NYU doctoral candidate, Zachary Ingbretsen, a research scientist who previously worked with Freeman and is now at Harvard University, and Eric Hehman, a post-doctoral researcher at NYU.

The researchers focused on the workings of the brain’s amygdala, a structure that is important for humans’ social and emotional behavior. Previous studies have shown this structure to be active in judging the trustworthiness of faces. However, it had not been known if the amygdala is capable of responding to a complex social signal like a face’s trustworthiness without that signal reaching perceptual awareness.

To gauge this part of the brain’s role in making such assessments, the study’s authors conducted a pair of experiments in which they monitored the activity of subjects’ amygdala while the subjects were exposed to a series of facial images.

These images included both standardized photographs of actual strangers’ faces as well as artificially generated faces whose trustworthiness cues could be manipulated while all other facial cues were controlled. The artificially generated faces were computer synthesized based on previous research showing that cues such as higher inner eyebrows and pronounced cheekbones are seen as trustworthy and lower inner eyebrows and shallower cheekbones are seen as untrustworthy.

Prior to the start of these experiments, a separate group of subjects examined all the real and computer-generated faces and rated how trustworthy or untrustworthy they appeared. As previous studies have shown, subjects strongly agreed on the level of trustworthiness conveyed by each given face.

In the experiments, a new set of subjects viewed these same faces inside a brain scanner, but were exposed to the faces very briefly — for only a matter of milliseconds. This rapid exposure, together with another feature known as “backward masking,” prevented subjects from consciously seeing the faces. Backward masking works by presenting subjects with an irrelevant “mask” image that immediately follows an extremely brief exposure to a face, which is thought to terminate the brain’s ability to further process the face and prevent it from reaching awareness. In the first experiment, the researchers examined amygdala activity in response to three levels of a face’s trustworthiness: low, medium, and high. In the second experiment, they assessed amygdala activity in response to a fully continuous spectrum of trustworthiness.

Across the two experiments, the researchers found that specific regions inside the amygdala exhibited activity tracking how untrustworthy a face appeared, and other regions inside the amygdala exhibited activity tracking the overall strength of the trustworthiness signal (whether untrustworthy or trustworthy) — even though subjects could not consciously see any of the faces.

“These findings provide evidence that the amygdala’s processing of social cues in the absence of awareness may be more extensive than previously understood,” observes Freeman. “The amygdala is able to assess how trustworthy another person’s face appears without it being consciously perceived.”


Story Source:

The above story is based on materials provided by New York UniversityNote: Materials may be edited for content and length.

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  • NoCrossNoCrescent

    Another nail in the coffin of “free will”.

  • D Rizdek

    It seems to me the “faces” that communicate low trustworthiness appear to be drawn, tight, the mouth down-turned, eyes narrowed or brows furrowed. Noting that reflects an ability to tell when someone else might be pissed and to err on the side of safety it would be wise to avoid contact or trust.

    But seeing a face that is relaxed and smiling…a more open face, a generous mouth, wider eyes gives an immediate sense of someone who is calmer or even happy and doesn’t set off alarm bells.

    But I don’t think it’s just the person that is judged but the person with their attitude or state of mind (good or bad) that shows forth in facial expression and perhaps even body language.

    • http://www.skepticink.com/tippling/ Jonathan MS Pearce

      I think the main point for me is what part of the brain is doing the functioning. Being an automatic functioning, conscious rationality plays no part.

      • D Rizdek

        Do you think it is learned…learned at such an early age that it become second nature…automatic? Or are you imagining it is something we are born with?

        • http://www.skepticink.com/tippling/ Jonathan MS Pearce

          Interesting. Well, in one sense, it matters no to a decision at a time since both are out of the control of the agent.

          I guess I think the brain is awesome at making very quick prior probability calculations, of making subconscious associative links. The clues and markers to these are so embedded n our subconscious and involve in our non-conscious calculations as to be effectively off the radar.

          It’s quite similar to the intuitive skills of the chicken sexers and the WW2 plane spotters:

          http://www.skepticink.com/tippling/2013/11/11/psychology-neuroscience-and-a-fundamental-lack-of-free-will/

        • http://www.skepticink.com/tippling/ Jonathan MS Pearce

          I answered this at length but it seems not to have registered

          Interesting. Well, in one sense, it matters no to a decision at a time since both are out of the control of the agent.

          I guess I think the brain is awesome at making very quick prior probability calculations, of making subconscious associative links. The clues and markers to these are so embedded n our subconscious and involve in our non-conscious calculations as to be effectively off the radar.

          It’s quite similar to the intuitive skills of the chicken sexers and the WW2 plane spotters:

          http://www.skepticink.com/tippling/2013/11/11/psychology-neuroscience-and-a-fundamental-lack-of-free-will/

          • D Rizdek

            “I answered this at length but it seems not to have registered”
            Oh, sorry I missed it. Is your answer in the post above…if so, I still miss it…or elsewhere?

      • Void Walker

        It seems that the more research we do on the mind, the more we find our “decisions” are largely motivated by subconcious activity within the brain. Great post John, it’s good to be back on Tippling.

        • http://www.skepticink.com/tippling/ Jonathan MS Pearce

          Rock on tommy! I’ve missed ya.