Indeed. I'm unsure as to why there appears to be a base assumption on this board that a degree in a one subject means you cannot have studied or have knowledge of another field! My lit. degree had modules in linguistics, the history of language evolution and sociology.

As for Dr. Asher, this is some further information about him, taken from his website.

Dr. James J. Asher originated the stress-free Total Physical Response approach to second language acquisition which is known internationally as TPR.

Dr. Asher developed the approach in 30 years of research. This research has resulted in TPR being used successfully in thousands of classrooms with children and adults learning languages such as English, Spanish, French, German, Chinese, Korean, Japanese, Arabic, Hebrew, and even the sign language of the deaf!

He is a emeritus Professor of Industrial Psychology and former Associate Dean at San Jose State University, the first public institution of higher learning in California, founded in 1857. His undergraduate work was completed at the University of New Mexico, a masters degree and doctorate at the University of Houston, and postdoctoral training at the University of Washington (linguistics), Stanford University (educational research), and the Defense Language Institute in Monterey, California (Arabic).

I'd say this makes him more than qualified not only in the field of linguistics, but also in education and educational development.