Research has demonstrated that nonhumans can acquire temporal discriminations across a wide range of durations. Such discriminations are also susceptible to environmental "biases." Killeen and Fetterman's (1988) Behavioral Theory of Timing (BeT) contends that rate of reinforcement biases organisms' temporal discriminations. The present study is an extension of Morgan, Killeen, and Fetterman (1993) into the domain of human behavior. Twelve subjects were trained to discriminate between eight different stimulus durations, and were then exposed to either a fast bias or a slow bias condition. The bias conditions did not produce the effects that have been observed with nonhumans, although some subjects were observed to "bisect" the range of durations at the geometric mean, as has been found with nonhumans. Several subjects reported that they counted to assist them in their discriminations.