Fast and accurate measurement of taste and smell thresholds using a maximum-likelihood adaptive staircase procedure

This paper evaluates the use of a maximum-likelihood adaptive staircase psychophysical procedure (ML-PEST), originally developed in vision and audition, for measuring detection thresholds in gustation and olfaction. The basis for the psychophysical measurement of thresholds with the ML-PEST procedure is developed. Then, two experiments and four simulations are reported. In the first experiment, ML-PEST was compared with the Wetherill and Levitt up-down staircase method and with the Cain ascending method of limits in the measurement of butyl alcohol thresholds. The four Monte Carlo simulations compared the three psychophysical procedures. In the second experiment, the test-retest reliability of ML-PEST for measuring NaCl and butyl alcohol thresholds was assessed. The results indicate that the ML-PEST method gives reliable and precise threshold measurements. Its ability to detect malingerers shows considerable promise. It is recommended for use in clinical testing.     

Questionable Intentions

Philosophical Studies -     

Visceral sensitivity as a mediator of outcome in the treatment of irritable bowel syndrome

Patients with irritable bowel syndrome (IBS) experience anxiety about visceral sensations, leading to avoidance behaviors and hypervigilance that maintain IBS symptoms. The current study used data from a clinical trial that compared a treatment aimed at reducing anxiety about visceral sensations (interoceptive exposure; IE) to an attention control (AC) and a CBT-based stress-management treatment (SM) to examine whether changes in visceral sensitivity mediated IBS symptom and quality of life outcomes. Data from participants who completed one of the three treatments (N = 76) were subjected to mediation analyses. Visceral sensitivity mediated treatment outcomes across all outcome measures and across all treatment groups, with no differences between IE and the other treatment groups. This finding suggests that psychosocial treatments for IBS may work by decreasing visceral sensitivity, and the degree to which visceral sensitivity is decreased is related to outcome, suggesting IE may be the preferable treatment option.