The effect of vibrato on the recognition of masked vowels

Five experiments on the identifiability of synthetic vowels masked by wideband sounds are reported. In each experiment, identification thresholds (signal/masker ratios, in decibels) were measured for two versions of four vowels: a vibrated version, in which FO varied sinusoidally around 100 Hz; and a steady version, in which F0 was fixed at 100 Hz. The first three experiments were performed on naive subjects. Experiment 1 showed that for maskers consisting of bursts of pink noise, vibrato had no effect on thresholds. In Experiment 2, where the maskers were periodic pulse trains with an F0 randomly varied between 120 and 140 Hz from trial to trial, vibrato slightly improved thresholds when the sound pressure level of the maskers was 40 dB, but had no effect for 65-dB maskers. In Experiment 3, vibrated rather than steady pulse trains were used as maskers; when these maskers were at 40 dB, the vibrated versions of the vowels were slightly less identifiable than their steady versions; but, as in Experiment 2, vibrato had no effect when the maskers were at 65 dB. Experiment 4 showed that the unmasking effect of vibrato found in Experiment 2 disappeared in subjects trained in the identification task. Finally, Experiment 5 indicated that in trained listeners, vibrato had no influence on identification performance even when the maskers and the vowels had synchronous onsets and offsets. We conclude that vibrating a vowel masked by a wideband sound can affect its identification threshold, but only for tonal maskers and in untrained listeners. This effect of vibrato should probably be considered as a Gestalt phenomenon originating from central auditory mechanisms.     

Effect of contralateral shock stimulation on laterality differences in the two shock threshold

Contralaterally presented shock was found to bring about marked changes in two shock threshold determined for the right finger but not for the left finger. The results are discussed in terms of a suggestion that the level of excitability of the left hemisphere may be more easily disturbed than that of the right hemisphere.     

Effect of ramp-like contours upon perceived size and detection threshold

Perceived widths and detection thresholds were measured for foveally viewed stimuli which were edged on two sides by luminance ramps. Perceived width approximated the distance between the midpoints of the ramps. It varied with the width of the ramps, but was unaffected by a five-fold change in the luminance of the stimulus. The detection threshold was higher for a ramp stimulus than for a normal stimulus of the same apparent width. The relationship between perceived width and detectability is consistent with a theoretical treatment based upon receptive-field mechanisms.     

Effect of anxiety reduction on children's school performance and social adjustment

This study tested the effect of reductions in children's anxiety over time on improvements in school performance and social functioning in the context of participation in a cognitive-behavioral intervention program. Participants included 40 children with high anxiety (6-13 years of age). Independent evaluators, children, and parents rated child anxiety; parents rated school performance; and children and parents rated social functioning. Measures were completed at preintervention, midintervention, and postintervention. Fixed-effects regression analyses and random-effects regression analyses indicated that decreased anxiety was predictive of improved school performance and social functioning over the course of the intervention. These findings suggest that changes in anxiety influence trajectories of children's scholastic and social functioning.     

The effect of set on the two-point tactual threshold

This experiment studies the influence of set on the two-point tactual threshold. The two-point limen (critical stimulus) was determined along the mid-longitudinal line of both volar and dorsal surfaces of the right forearms of seven university students. Test-stimuli were selected at 3 mm. steps both up and down from each of the critical stimuli. Each of these test-stimuli was presented separately, the critical stimulus being interpolated 30 times in each test of the series. The proportions of two-point and one-point responses to the critical stimulus were then determined again in a control series. It was found that, as the test-stimulus deviated in the positive direction from the critical stimulus, the proportion of two-point responses to the critical stimulus increased, reached a maximum and then began to decline. A similar rise and fall in one-point responses were found in the opposite direction. The results were explained by Adaptation Level Theory.     

At the threshold of knowledge

We explore consequences of the view that to know a proposition your rational credence in the proposition must exceed a certain threshold. In other words, to know something you must have evidence that makes rational a high credence in it. We relate such a threshold view to Dorr et al.’s (Philosophical Studies 170(2):277–287, 2014) argument against the principle they call fair coins: “If you know a coin won’t land tails, then you know it won’t be flipped.” They argue for rejecting fair coins because it leads to a pervasive skepticism about knowledge of the future. We argue that the threshold view of evidence and knowledge gives independent grounds to reject fair coins.