Effects of attentional set and rhythmic complexity on attending.

In a target detection task involving sustained attentional monitoring, rhythmic properties of tone sequences were found to affect detection performance (area under receiver-operating characteristic curves) and reaction times. Alternating tone frequencies (high, low) formed three different recurrent rhythms (binary, trinary, mixed) which varied in complexity. Attentional set was also manipulated so that participants attended either to tones of both frequencies (divided) or to only the higher of the two tones (selective). The most interesting finding involved an interaction between attention set and rhythm, indicating that selective attending is enhanced by the most complex (mixed) rhythm, whereas divided attending tends to be best with the simplest rhythm (binary). Results are discussed in terms of a theory of dynamic attending, in which it is assumed that listeners actively use attending oscillators to direct attending.