Do human cognitive differences in information processing affect preference and performance of CAPTCHA?

A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a widely used security defense mechanism that is utilized by service providers to determine whether the entity interacting with their system is a human and not a malicious agent. Common design practices of current CAPTCHA schemes barely take into account cultural, contextual, and individual cognitive characteristics and abilities of users. Motivated by recent research which underpins the necessity for designing more user-friendly CAPTCHA, this paper investigates the effect of users' cognitive styles and cognitive processing abilities towards preference and task performance of CAPTCHA challenges. In the frame of the reported research, two user studies were conducted. The first study (n=131) explored the effect of users' cognitive styles (Verbal/Imager) on user preference and task performance of two complementary types of CAPTCHA mechanisms; text-recognition and image-recognition. The second study (n=125) explored the effect of users' cognitive processing abilities (speed of processing, controlled attention, working memory capacity) on task performance in regards with different levels of complexity of both text-recognition and image-recognition CAPTCHA. Analysis of results revealed interaction effects of users' cognitive processing characteristics towards preference and performance of CAPTCHA, suggesting that individual differences at such an intrinsic level are important to be considered for designing more usable and user-centric CAPTCHA challenges. We study the effects of cognitive factors on CAPTCHA preference and performance.Verbals prefer and solve significantly faster text CAPTCHA.There is a growing trend of Imagers preferring and solving faster image CAPTCHA.Users with enhanced cognitive processing abilities solve CAPTCHA faster.Implications about the design of personalized CAPTCHA are discussed.