The “subjective” pupil old/new effect: Is the truth plain to see?

• We examined false memory of action verbs with a recognition task and pupillometry.
• We found both a “real” and a “subjective” pupil old/new effect.
• We found manipulatory verb effect on both recognition and pupil data.
• Findings support the strength-of-memory trace account and embodied language theories.

Human memory is an imperfect process, prone to distortion and errors that range from minor disturbances to major errors that can have serious consequences on everyday life. In this study, we investigated false remembering of manipulatory verbs using an explicit recognition task and pupillometry. Our results replicated the “classical” pupil old/new effect as well as data in false remembering literature that show how items must be recognize as old in order for the pupil size to increase (e.g., “subjective” pupil old/new effect), even though these items do not necessarily have to be truly old. These findings support the strength-of-memory trace account that affirms that pupil dilation is related to experience rather than to the accuracy of recognition. Moreover, behavioral results showed higher rates of true and false recognitions for manipulatory verbs and a consequent larger pupil diameter, supporting the embodied view of language.