Assessment of hemispheric asymmetry: Development and psychometric evaluation of a chimeric face test.

Background: Anomaly in hemispheric functioning has been linked with various psychiatric conditions. However, most of the procedures used to assess hemispheric asymmetry in clinical population require special training and/or complex procedures and some of the measures suffer from such methodological problems that undermine their utility for clinical use. Further, the available economical procedures such as chimeric face test (CFT) utilize facial expression of emotions posed by western expressers and are therefore less valid measures in Indian context. Aim: Taking these limitations into account, the present study makes an attempt to develop a CFT (using facial affect photographs of Indian expressers) as an alternative and economical procedure for the assessment of hemispheric asymmetry. Materials and Methods: Using the happy and neutral expressions of eight Indian expressers, 32 chimeric faces were developed by combining the half happy and half neutral expressions. These 32 chimeric faces were presented in pairs (arranged in top-bottom fashion) in booklet form to 225 right-handed participants. Using the contemporary item analytic procedure, finally 22 pairs of chimeric faces that showed satisfactory psychometric properties were retained. These 22 pairs of chimeric faces formed the final CFT. The psychometric properties of the various items as well as that of the whole CFT were found satisfactory. Results: All the items were found reliable and valid as indicated by item-total correlation and alpha-if-item deleted. The internal consistency of the CFT was also found to be highly satisfactory (Cronbach's alpha =.80). Further, the participants on the average showed a right hemispheric advantage on the CFT that provide support to its validity. The findings of intermediate analysis of the data of an ongoing project also provide preliminary evidence for the validity of the CFT. Conclusion : The CFT is a reliable and valid measure to assess hemispheric asymmetry in the processing of facial emotions and may prove to be an economical and useful tool in clinical setting.