Attentional switching when listeners respond to semantic meaning expressed by multiple talkers

The "cocktail party problem" asks how we know what one person says when others are speaking at the same time. In our simulated cocktail party, a subject sits among multiple talkers, each telling a different story. A sequence of questions are drawn from the various stories and presented visually for subjects to answer with manual responses. One talker is identified (visually) as the primary, the one from whom a majority of questions are taken. Pay is based on correct answers, and attention is assessed by comparing response accuracy on questions from the primary and from the other talkers. With interest in the difficulty faced by older and often hearing-impaired listeners in multi-talker environments, the present experiment looks at the speed of shifting attention. All questions are from a primary, chosen at random from question to question. The speed of shifting is measured by varying the time from when the new primary is identified to the moment when the relevant information appears in that story. In a related study, bilingual subjects must shift attention to talkers speaking either English or Spanish. This allows determination of the additional time needed to switch languages within this multi-talker environment.