A reduction of stimulus intensity resulted in decreased accuracy at all stimulus durations.
However, numerous human and animal studies have previously reported a deviation from linearity for short stimulus durations (<4 s).
A series of MR images of the visual and motor cortexes were acquired during visual stimulation and finger tapping, respectively, at five different stimulus durations (SD).
However, perceived smear was substantially greater in the fixation condition for stimulus durations that were longer than the period of dot motion.
In contrast, the stimulus durations were judged longer after viewing the frightening films that were judged to increase the emotion of fear and the level of arousal.
Detection was also examined for a range of stimulus durations, rates of change in interaural delay (i.e., velocity), and extent of change in interaural time difference (i.e., 'distance'distance
However, such small differences fall below the perceptual difference limen, which is, for stimulus durations of 300 ms and more, at about 25 30 ms according to empirically based estimations of Lehiste [57] or Klatt and Cooper [58].
Experiments on healthy volunteers showed that all three hemodynamic-weighted signals responded nonlinearly to stimulus durations less than 4 s, with the degree of nonlinearity becoming more severe as the stimulus duration decreased.
Furthermore, we show that prolonged stimulus durations and repetition times of 3 s still allow an effective suppression of speech-related artifacts in fluent as well as in nonfluent speakers.
Highly intense stimulation, better tolerated by human subjects for short stimulus durations, causes early CMRO2 increase, and thus, the experimental design utilized in this study is better for detecting the initial dip than standard fMRI designs.
Although most human fMRI studies employ the event-related task design, in which the stimulus duration is short, few studies have investigated the relationship between BOLD signals and evoked potentials at short stimulus durations.
