Spotting FACES How many faces can you spot in this picture? Bev Doolittle (1984) - The Forest has Eyes Introduction 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? References 1. Purcell & Stewart (1986), Perception & Psychophysics, 43(4), pgs Goren & Julesz (1990), Perception, 19(1), pgs Ro, Russell & Lavie (2001), Psychological Science, 12(1), pgs Rolls et. al. (1994), Experimental Brain Research, 101(3), pgs 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! However, performance improved vastly if the image was an upright face 1. Upright faces could appear for shorter periods than either inverted or scrambled faces (see Fig. 1 for examples) and still be detected just as accurately. The claim was that faces were faster to be detected, over other less-familiar visual images. That is to say, face images might be able to capture one's visual attention. They named this, the Face-Detection-Effect ! Fig. 1 Upright, Inverted and Scrambled faces...more experiments In 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 configuration 2 e.g. 2a Intriguingly, there were faster detection times for lines that made 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. Now, wasn't that interesting! 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 objects 3. a)b) c)d) Fig. 2 Display arrays for line detection Is the brain a face-spotter ? Fig. 3 Change-detection experiment So, 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. Invasive procedures into a monkey's brain shows that there are neurons within the brain that are particularly 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.