Smiling Faces Are Better for Face Recognition

This challenges the common notion of using neutral face images for face recognition. As smile is the most common expression, it can be used for optimizing performance when tens of thousands or even million faces are to be recognized. 

To test this, Yakoob and Davis, from University of Maryland, conducted an experiment in two parts. Two databases containing neutral and smiling face images of same person in each database were used. For first part of experiment, 10 subjects from first database were used. The discrimination power was calculated for smiling and neutral faces. 

It was found that the discrimination power was more for smiling expression than for neutral expressions which showed that smiling faces are better in face recognition.

In second part of the experiment, more face images were added from second database. In first stage of second part, 0-15 faces were added. Then in second stage, 0-40 faces were added again. The average discriminating power was calculated. 

In both stages, the average discriminating power of smiling faces was more than the average discriminating power of neutral faces which again showed that smiling faces are better for face recognition. 

To detect a face of person in video clips, expressive faces such as smiles will be more cooperative for access applications as well as surveillance purposes.

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Reference – Yaser Yakoob and Larry Davis. Computer Vision Laboratory, University of Maryland, College Park, MD 20472. Research paper name - Smiling Faces Are Better for Face Recognition. Published In - Proceedings of the Fifth IEEE International Conference on Automatic Face and Gesture Recognition (2002).

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How We Smile While Lying

Using a smile to conceal negative or genuine feelings can be a smart thing to avoid dispute or exposing honest feelings which can create problems. Ekman et al. conducted an experiment to know the difference between how people smile genuinely and how they smile when they are lying about pleasant feelings. 

47 student nurses were recruited for this study. They were videotaped while watching two short films. One short film was arousing pleasant feelings and another, arousing upsetting feelings.  Two scenarios were set to give their responses to an interviewer. In honest scenario, they were asked to discuss their honest feelings about film arousing pleasant feelings. 

In deceptive scenario, they had to convince interviewer that they experienced pleasant feelings while watching film arousing upsetting and depressing feelings.

Two types of smiles were distinguished as felt happy smiles and masking smiles. Felt happy smiles were identified by the activity of muscles around the eyes along with corners of mouth raised.

While masking smile is identified by raising corners of mouth only. It was found that when enjoyment was experienced, felt happy smiles occurred more often than masking smile. 

When subjects attempted to hide strong negative emotions, masking smile occurred more often than felt happy smiles. When you don’t see any activity around the eyes when someone is smiling; tell them you caught them lying and ask what is that they are hiding.

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Reference – Paul Ekman, Wallace Friesen, University of California, San Francisco. Maureen O’Sullivan, University of San Francisco. 

Research paper name – Smiles When Lying. 

Published in – Journal of Personality and Social Psychology (1988)

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