Switching time between overt and covert speech: Generative attention

Four experiments investigated a new phenomenon: the existence of a very large switching time effect that occurs from rapidly alternating between overt and covert (mouthed) speech. This is referred to as an intensity switching effect, and the time taken for each switch is, in itself, long enough for a spoken or mouthed character (letter or digit) to be produced. In Experiments 1 and 2, the intensity switching effect was shown to be different from the switching that occurs between categories of materials (letters and digits) because it is both much larger and much more resistant to practice effects. The intensity switching effect was also shown to be distinct from a memory load effect, since it holds even for perceptually available lists. In Experiments 3 and 4, the issue of a peripheral vs. a central origin of intensity switching was addressed. Evidence was found for a central origin. In addition, two models -of response intensity representation were contrasted: a symbolic or digital model, with intensity altered by parameter substitution, and an analog model, with intensity represented by a moving pointer on an intensity continuum. The results supported the symbolic model. It is concluded that the intensity switching effect is a measure of control processes at work in altering the intensity parameters of the vocal response system.