The concurrent use of three implicit measures (eye movements, pupillometry, and event-related potentials) to assess receptive vocabulary knowledge in normal adults.

Recent years have seen the advent and proliferation of the use of implicit techniques to study learning and cognition. One such application is the use of event-related potentials (ERPs) to assess receptive vocabulary knowledge. Other implicit assessment techniques that may be well-suited to other testing situations or to use with varied participant groups have not been used as widely to study receptive vocabulary knowledge. We sought to develop additional implicit techniques to study receptive vocabulary knowledge that could augment the knowledge gained from the use of the ERP technique. Specifically, we used a simple forced-choice paradigm to assess receptive vocabulary knowledge in normal adult participants using eye movement monitoring (EM) and pupillometry. In the same group of participants, we also used an N400 semantic incongruity ERP paradigm to assess their knowledge of two groups of words: those expected to be known to the participants (high-frequency, familiar words) and those expected to be unknown (low-frequency, unfamiliar words). All three measures showed reliable differences between the known and unknown words. EM and pupillometry thus may provide insight into receptive vocabulary knowledge similar to that from ERPs. The development of additional implicit assessment techniques may increase the feasibility of receptive vocabulary testing across a wider range of participant groups and testing situations, and may make the conduct of such testing more accessible to a wider range of researchers, clinicians, and educators.