N400, an event-related brain potential (ERP) waveform elicited by meaningful stimuli, is normally reduced by stimulus repetition (N400 repetition priming), and relatedness between the eliciting stimulus and preceding ones (relatedness priming). Schizophrenia patients' N400 relatedness priming deficits suggest impairment in using meaningful prime stimuli to facilitate processing of related concepts in semantic memory. To examine whether this deficiency arises from difficulty activating the prime concept per se, as indexed by reduced N400 repetition priming; or from impaired functional connections among concepts in semantic memory, as reflected by reduced relatedness priming but normal repetition priming; we recorded ERPs from 16 schizophrenia patients and 16 controls who viewed prime words each followed at 300- or 750-ms stimulus-onset asynchrony (SOA) by an unrelated, related or repeated target word, or a nonword, in a lexical-decision task. In both groups, N400s were largest (most negative) for unrelated, intermediate for related, and smallest for repeated targets. Schizophrenia patients exhibited subnormal N400 relatedness priming at the 300-ms SOA, but normal repetition priming at both SOAs, suggesting that their impairment in using primewords to activate related concepts results from abnormal functional connections among concepts within semantic memory, rather than inability to activate the prime concept itself.

We used a novel stimulus set of human and robot actions to explore the role of humanlike appearance and motion in action prediction. Participants viewed videos of familiar actions performed by three agents: human, android and robot, the former two sharing human appearance, the latter two nonhuman motion. In each trial, the video was occluded for 400 ms. Participants were asked to determine whether the action continued coherently (in-time) after occlusion. The timing at which the action continued was early, late, or in-time (100, 700 or 400 ms after the start of occlusion). Task performance interacted with the observed agent. For early continuations, accuracy was highest for human, lowest for robot actions. For late continuations, the pattern was reversed. Both android and human conditions differed significantly from the robot condition. Given the robot and android conditions had the same kinematics, the visual form of the actor appears to affect action prediction. We suggest that the selection of the internal sensorimotor model used for action prediction is influenced by the observed agent's appearance.

Despite growing evidence of young adults neurally pre-activating word features during sentence comprehension, less clear is the degree to which this generalizes to older adults. Using ERPs, we tested for linguistic prediction in younger and older readers by means of indefinite articles (a’s and an’s) preceding more and less probable noun continuations. Although both groups exhibited cloze probability-graded noun N400s, only the young showed significant article effects, indicating probabilistic sensitivity to the phonology of anticipated upcoming nouns. Additionally, both age groups exhibited prolonged increased frontal positivities to less probable nouns, although in older adults this effect was prominent only in a subset with high verbal fluency (VF). This ERP positivity to contextual constraint violations offers additional support for prediction in the young. For high VF older adults, the positivity may indicate they, too, engage in some form of linguistic pre-processing when implicitly cued, as may have occurred via the articles.