The shape of Word-of-Mouth response function

A consumer may not be affected by all positive recommenders due to limitations of cognitive capacity. This limitation (of cognitive capacity) results in two different response functions for the size of positive recommenders: One is an S-shaped function which assumes that the second and third sources (recommenders) have greater additional impact than the first source, and the other is a concave-shaped function which assumes that the first source (recommender) is more influential than the second and the third sources. In this paper we operationalize volume of Word-of-Mouth as the total number of positive Word-of-Mouth senders and using two conjoint studies empirically investigate whether the relationship between the volume of Word-of-Mouth and its impact follows a concave-shaped function or an S-shaped function. The two conjoint studies support the concave-shaped response for the volume of Word-of-Mouth.