No abstract

It is generally believed that selective adaptation effects in speech perception are due to a reduction in sensitivity of auditory feature detectors. Recent evidence suggest that these effects may derive instead from contrast. In a further test of the contrast hypothesis, we conducted two experiments each involving both adaptation and contrast sessions with matching stimulus sets. During the adaptation sessions of Experiment 1, subjects identified two series of velar stimuli varying in voice onset time, [ga]-[kha] and [gi]-[khi], before and after adaptation with of the following stimuli: [ga], [kha], [gi], and [khi]. In the contrast session, subjects identified either of two ambiguous test items (drawn from near the phonetic boundaries of the [ga]-[kha] and the [gi]-[khi] series) following a single presentation of [ga], [kha], [gi], or [khi]. For both the adaptation and contrast sessions, (a) the [--a] test items were more greatly affected (in a contrast direction) by the [--a] than by the [--i] adaptor/context stimuli, and (b) the [--i] test items were not differentially affected by the [--1] and [--i] adaptor/context stimuli. An analogous design was used in Experiment 2, except that the stimulus sets varied in pitch rather than vowel quality. For both the adaptation and contrast sessions, the test items were not differentially affected by the pitch of the adaptor/context stimulus. These parallel results provide further evidence that adaptation effects are actually a form of contrast.

These findings emphasize the importance of clients' perspectives in treatment planning and suggest that clinicians may overlook the smaller incremental steps toward improvement that are valued by clients.

In 2005, Blue Cross Blue Shield of Kansas City initiated a comprehensive worksite wellness program designed to impact employer culture and to assist healthy employees to stay at low risk and to reduce risk levels for those at moderate or high risk. Fifteen employer groups (9637 employees) participated in the A Healthier You (AHY) program for 3 consecutive years, 2006-2008. The results of health risk appraisals and biometric screening were used to evaluate program impact. Among the 4230 employees (44.0% of eligible employees) who completed health risk appraisals in all 3 years, 85.8% of individuals in the low-risk category in 2006 remained at low risk in 2008. There were also improvements in other risk categories, with 39.9% of those in the medium-risk category and 48.9% of those in the high-risk category in 2006 moving to a lower risk category in 2008. There were improvements in blood pressure control and total cholesterol, but no improvement in weight control. To assess financial and utilization outcomes, claims for the participating employer groups were compared to those for 7 employers (3800 employees) who did not participate in AHY in 2006-2008. Although none of the utilization measures was statistically different, the AHY groups had significantly smaller increases in both overall and emergency room costs per member per month. The AHY program now has over 180 employer groups, which will allow future evaluations to examine the impact of the program on a much larger population and to focus on the comparative effectiveness of different intervention strategies across implementations.

It is generally believed that selective adaptation effects in speech perception are due to a reduction in sensitivity of auditory feature detectors. We have recently presented evidence that these effects may derive instead from response contrast. In a further test of the contrast hypothesis, we conducted both an adaptation and a contrast experiment with matching sets of stimuli. In the adaptation experiment, subjects identified two series of velar stimuli varying in VOT, [ga-kha] and [gi-khi], before and after adaptation with each of the following test stimuli: [ga], [kha], [gi], and [khi]. In the contrast experiment, subjects identified either of two ambiguous test items (drawn from near the phonetic boundaries of the [ga-kha] and the [gi-khi] series) following a single presentation of [ga], [kha], [gi], or [khi]. For both the adaptation and the contrast experiments, (1) the [Ca] test items were more greatly affected (in a contrast direction) by [Ca] than by the [Ci] adaptor/context stimuli, and (2) the [Ci] test items were not differentially affected by the [Ca] and [Ci] adaptor/context stimuli. These parallel results suggest that vowel contingent adaptation results may well be due to response contrast rather than sensory fatigue.