Are psychophysical functions derived from line bisection reliable?

Abstract

Psychophysical functions are used to characterize both normal perception and altered perception among patients with neglect, yet the reliability of these functions is rarely examined. The present study examined two-week, test-retest reliability for power functions derived from line bisection data among 58 normal, young and old, male and female subjects. Power function exponents and constants were, at best, moderately reliable over time. The size of the exponent tended to decrease at retesting. Reliability coefficients varied by age and gender; they were highly significant for young men, marginally significant for older men, and non-significant for women. Race influenced reliability as coefficients were significant for Caucasian subjects but not for African American subjects. Age and gender effects in this study parallel those in the literature on pseudoneglect, and they may reflect hemispheric differences in visuo-spatial processing, magnitude estimation, or both. (JINS, 2003, 9, 72–78.)

Biases in Attentional Orientation and Magnitude Estimation Explain Crossover: Neglect is a Disorder of Both

“…Power functions applied to cancellation data show that the total number of cancellation targets predicts the number neglected (Chatterjee, Mennemeier, & Heilman, 1992b), regardless of the spatial location of neglected cancellation targets (Chatterjee, Mennemeier, & Heilman, 1992c), again suggesting that quantitative and spatial aspects of neglect are dissociable. Power functions account for extremely large portions of variance on all these tests in normal subjects and patients with neglect (Pierce et al, 2003;Mennemeier, Vezey, Lamar, et al, 2002;Chatterjee, 1995;Chatterjee, Dajani, et al, 1994;Chatterjee, Mennemeier, & Heilman, 1992a, 1992b. The quantitative errors made by patients with neglect appear to represent a true deficit in magnitude estimation because they are not merely restricted to estimates of length or to "spatial" stimuli.…”

“…This might be due either to experimental factors such as the type of task (Rueckert et al, 2002) or nonexperimental factors such as the age or sex of subjects (Pierce et al, 2003), as such factors may influence attentional orientation and magnitude estimation. The truly novel finding of this study concerned the degree to which the physical presence of a line anchors attentional orientation.…”

“…The crossover effect is influenced by the sex and age of normal subjects. Pierce, Jewell, and Mennemeier (2003) found that normal male subjects, especially young men, produced reliable patterns of crossover, whereas women did not, regardless of age. Confounds due to sex of subject could have obscured crossover in the Rueckert et al study, which included twice as many women as men.…”

“…Hypotheses concerning magnitude estimation were tested using the power function exponent and constants as summary variables. Perceived line length was derived from the line bisection data, in Experiments 1-3, by doubling the distance from the attended end of the line to the bisection mark (see Pierce et al, 2003;Mennemeier, Vezey, Lamar, et al, 2002;Chatterjee, 1995;Chatterjee, Dajani, et al, 1994;Chatterjee, Mennemier, & Heilman, 1994). The right end of the line is assumed to be the attended end among normal subjects and RHL patients, whereas the left end of the line is assumed to be the attended end among LHL patients.…”

Reaction time assessment in children with ADHD

“…Psychophysical is a quantitative branch of the study of the perception, which evaluate the relations between observed stimuli and response and a form of measurement used in most psychophysical studies is through the reaction time 9,10 . In this task, the individual has to compare the order of presentation of two stimuli presented in the visual field at different intervals.…”