Spotting FACES

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Experimental findings In 1986, two American scientists discovered that if you simply asked individuals to spot a briefly presented image (~50msecs.) against a blank background, they would do miserably! - PowerPoint PPT Presentation

Text of Spotting FACES

  • Spotting FACESHow many faces can you spot in this picture? Bev Doolittle (1984) - The Forest has EyesIntroduction

    Look to the picture on the right and back again quickly.

    What was it that caught your attention upon first glance?Do you remember how many items were on the table?What about the table-cloth? Was it well-pressed or wrinkly?

    Now, if you are anything like the most of us, you wouldn't have a clue!?!? (although mummies do seem to be freakishly good with the table-cloth question...)

    Do you remember the people in the picture? How is it that you noticed their faces and not the other objects? What is it about faces that demand our immediate attention upon first-sight?References1. Purcell & Stewart (1986), Perception & Psychophysics, 43(4), pgs. 355-366.2. Goren & Julesz (1990), Perception, 19(1), pgs. 5-163. Ro, Russell & Lavie (2001), Psychological Science, 12(1), pgs. 94-994. Rolls et. al. (1994), Experimental Brain Research, 101(3), pgs. 473-484...more experimentsIn fact, this effect seems be present even with simple line configurations that resemble faces. When participants were asked to find the straight line in an array like those displayed in Fig. 2, they were faster to do so if the line made up a face-like configuration2 e.g. 2a Intriguingly, there were faster detection times for lines thatmade up a face-configuration, although participants were never actually asked to look for a face; in fact, very few participants even noticed the presence of a face-like configuration in the displays used e.g. 2d.In another experiment, participants were asked to decide which of 6 objects had changed across 2 presentations that followed each other. Fig. 3 shows the experimental time-line.

    Participants were 90% accurate whenever a face was changed, but less accurate with spotting changes with other objects3.a)b)c)d)Fig. 2 Display arrays for line detectionIs the brain a face-spotter ?Fig. 3 Change-detection experimentSo, why are we so good and fast at spotting faces in a visual scene?

    On a parting note, let us explore how the monkey's brain activates to faces. Invasiveprocedures into a monkey's brain shows that there are neurons within the brain that areparticularly excited by faces and not so, by scrambled faces. See Fig. 4.

    Therefore, we might say that faces are of such great social relevance to humans that we have developed a special tuner in our brains that fires specifically to the presence of a face. This might explain why we react so speedily to faces.The work presented is part of a current post-grad study into face-perception at University of Manchester, Dept. of Psychology.Chuang, L. & Lander, K.