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Abstract

We implemented an internet version of the well-known memory game on our webserver to study viewpoint influences on face recognition. We were able to attract more than 200 anonymous participants through the website. Players had to find eight face pairs in a 4-by-4 card array. There were three different levels at which the game could be played. Level 1: A pair consisted of two identical frontal faces illuminated from the front. Level 2: A pair consisted of two symmetric views of a face: 45 and -45 deg. The 45 deg view was illuminated from the front, the -45 deg view was illuminated from -45 deg. Level 3: A pair consisted of two different views: frontal and 45 deg, both illuminated from the front. Players could only reach the next level by finishing the previous one. Quitting the game was allowed at any time. We analyzed the number of errors participants made until finishing each level. Result: Players made more errors on level 3 than on level 2, and more on level 2 than on level 1. To test for possible learning effects (the faces were kept the same in all levels) another group of players played the levels in a different order. However, error rates were independent of the order in which the levels were played. Apparently, using bilateral symmetry inherent in the face seems to be easier (in the sense of less errors made), than to make use of a common illumination direction. This is consistent with a study by Troje and Bu¨lthoff (Vision Research 38,1,1998) where a same/different paradigm in a precisely timed lab experiment using untextured faces was employed. The results of our game paradigm show that their results can be extended to other paradigms, longer presentation times, and textured faces. When lab members (n=16) who were familiar with the faces (their colleagues) played the game, their error over all levels did not vary, suggesting a rather image-independent but semantic-dependent behavior. Conclusion: The usage of a game paradigm challenges and motivates participants and allows to draw conclusions about mechanisms in face recognition.