ABSTRACT
The internal clock is a putative mental structure whose function is to scale the temporal attributes of events. The entire timing process involves fairly low-level sensory specific structures, such as the internal clock, and higher level general purpose structures, such as working and reference memory, which are involved in other forms of information processing. Timing is considered to be a cognitive process because of the observation that subjects (humans and rats) control the way in which stimulus information is integrated over time (e.g., Brown, 1985; Church, 1984; Thomas & Weaver, 1975; Zakay, Nitzan, & Glicksohn, 1983). My colleagues and I have recently shown that rats act as if they use a run mode and an event mode to integrate stimulus duration and number and that both of these modes involve temporal integration processes that can be conducted concurrently (e.g., Meck, 1987c; Meck & Church, 1983, 1984b; Meck, Church, & Gibbon, 1985). Other work has shown that rats are able to run, stop, and reset their internal clocks much like a man-made stopwatch with storage capabilities (e.g., Meck, Church, & Olton, 1984; Roberts, 1981; Roberts & Church, 1978). On the other hand, the quantification of brain-stimulation reward (BSR) has not often been thought of as a cognitive process. It is most frequently considered to involve sensory mechanisms the functions of which are carried out automatically and may simply reflect the most basic properties of neuronal spatial-temporal integration (Wauquier & Rolls, 1976).
