The purpose of this study was to compare the role of frequency selectivity in measures of auditory and vibrotactile temporal resolution. In the first experiment, temporal modulation transfer functions for a sinusoidally amplitude modulated (SAM) 250-Hz carrier revealed auditory modulation thresholds significantly lower than corresponding vibrotactile modulation thresholds at SAM frequencies greater than or equal to 100 Hz. In the second experiment, auditory and vibrotactile gap detection thresholds were measured by presenting silent gaps bounded by markers of the same or different frequency. The marker frequency F1 = 250 Hz preceded the silent gap and marker frequencies after the silent gap included F2 = 250, 255, 263, 310, and 325 Hz. Auditory gap detection thresholds were lower than corresponding vibrotactile thresholds for F2 markers less than or equal to 263 Hz, but were greater than the corresponding vibrotactile gap detection thresholds for F2 markers greater than or equal to 310 Hz. When the auditory gap detection thresholds were transformed into filter attenuation values, the results were modeled well by a constant-percentage (10%) bandwidth filter centered on F1. The vibrotactile gap detection thresholds, however, were independent of marker frequency separation. In a third experiment, auditory and vibrotactile rate difference limens (RDLs) were measured for a 250-Hz carrier at SAM rates less than or equal to 100 Hz. Auditory RDLs were lower than corresponding vibrotactile RDLs for standard rates greater than 10 Hz. Combination tones may have confounded auditory performance for standard rates of 80 and 100 Hz. The results from these experiments revealed that frequency selectivity influences auditory measures of temporal resolution, but there was no evidence of frequency selectivity affecting vibrotactile temporal resolution.

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This article explores the basis of the public debate between Darwinian evolution and creationism. Using dramatic analysis, we show that the source for the debate is due to what we call "Darwin's Dilemma," which is found in Darwin's Origin of Species. In the Origin, Darwin extends the mechanistic metaphor featured in Enlightenment science by devising the concept of "natural selection." In the process, however, he also ascribes a motive to nature, which moves his theory outside the boundaries of Enlightenment science. We show that he is aware of this dilemma in his theory, and that he tries to pass it off as a metaphorical maneuver for the sake of brevity. Darwin's inability to resolve this dilemma, however, opens the door for purveyors of creationism and intelligent design. Indeed, much of the debate today over Darwinian evolution still pivots on our inability to come to terms with Darwin's dilemma.Darwin's On the Origin of Species has been a central concern of science writing since it was first published in 1859. A visit to the science writing section at the local bookstore will affirm that a whole cottage industry has developed around this still controversial monograph. In these books, the defenders of creationism, intelligent design, and evolutionary biology square off, jabbing and parrying each other with claims and proofs. Meanwhile, champions of creationism and intelligent design, like knight errants, make regular stops at college campuses and houses of worship, drawing local evolutionary scientists into well-attended debates about evolution.

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