Exploring User Experiences Across Different Image-Based CAPTCHA Types

This study empirically analyzes the impact of image-based CAPTCHA types and difficulty levels on user experience (usability, security, discomfort, and cognition) through experiments with developed prototypes. A preliminary study with 15 participants refined difficulty levels, followed by a main experiment with 32 participants in face-to-face trials. High-difficulty multiple-image selection CAPTCHAs increased discomfort and cognitive load, especially for users with lower digital literacy, while slide-based and receipt entry CAPTCHAs were rated higher in usability due to their intuitive design. By addressing the gap in prior research focused on security, this study provides UX design guidelines for CAPTCHA development and offers insights into balancing security and usability in future implementations.