• We propose a novel way of computing the change in size of a subjective time unit (S), based on a ratio score of produced durations, and investigate how this S-ratio changes as a function of Quadrato motor training, Vipassana meditation and a control condition of restful wakefulness, using different participants for each condition. The similar trend for both peak alpha frequency (PAF) and the S-ratio following motor training is summarized by their significant correlation of 0.57. We discuss the relationship between PAF, time production, and movement, drawing implications for the rate of functioning of an internal clock. The task of time production perhaps best reflects the speed or rate of functioning of an internal clock (Baudouin et al., 2006). If the required duration is 10 sec, individual A might produce a duration of 8 sec, individual B one of 10 sec and individual C one of 12 sec — though for all three individuals, produced duration is subjectively viewed as lasting 10 sec. Individual B exhibits veridical time perception (i.e., produced duration = required duration; 1 subjective second = 1 sec). Individual A would be viewed as having a faster internal clock (with each subjective second lasting 0.8 sec), and individual C would be viewed as having a slower internal clock (with each subjective second lasting 1.2 sec). If these same individuals are consistent (i.e., their clock speed is consistent), and they are asked to produce durations of 4, 6, 8, 10, 12, 14 and 16 sec, say, then a psychophysical function can be easily derived for each individual (with slopes being 0.8, 1.0 and 1.2, respectively). This is the case, whether the data are consistent with a linear function (Allan, 1979) as here, or with a power function (which can be subsequently linearized using a log-log plot). This is also the case whether the individual employs chronometric counting (Bizo et al., 2006; Brown et al., 1995) or not. Our data are drawn from two current studies using the same procedure for time production with online EEG recording (Glicksohn et al., 2009a, 2009b). The online EEG enables us to provide a different indicator of internal clock speed, namely peak alpha frequency (PAF). The longer the produced duration (individual C), the slower the internal clock — and "if the alpha rhythm drives the internal clock, alpha frequency should decrease as time productions increase" (Adam et al., 1971, p. 134) — hence the decrease in PAF (Coffin & Ganz, 1977). We contrast the data for males and females, given that males make relatively longer time productions (Block et al., 2000, p. 1341; Zakay & Block, 1997, p. 13). Our main goal, however, is to bridge between psychophysical and chronometric-counting approaches, assuming that while longer produced durations could be indicative of the fact that the internal clock is "…producing pulses at a considerably decreased rate"

publication date

  • January 1, 2010