Response bias affects perceptual asymmetry scores and performance measures on a dichotic listening task

Development and Validation of Quadri Condition Dichotic Double Word Test in Kannada

INTRODUCTION

Dichotic listening (DL) is a test where auditory stimuli are presented simultaneously to each ear. DL has clinical applications in assessing APD, schizophrenia, and brain injury. It is sensitive to hemisphere differences and has been used to study language lateralization. The study aimed to develop, validate, and establish norms for a Quadri condition Dichotic Double Word Test (free recall, forced right, forced left, and switch attention) in the Kannada language (DDWT-K).

METHODS

This study was carried out in two phases. Phase 1 aimed to develop and validate the DDWT-K and phase 2 involved data collection. The developed novel dichotic test was administered on 100 normal-hearing adults in four conditions - free recall, forced right, forced left, and switch attention.

RESULTS

The results showed significant ear differences in free recall condition indicating right ear advantage. The switch attention condition showed slightly poorer performance when compared to both the forced attention condition indicating greater task difficulty. The test-retest reliability was above 0.7 for all the conditions indicating good reliability.

CONCLUSIONS

The findings demonstrated the best preservation of the original dichotic effects and hence ready for clinical use.

Test position effects on hit and false alarm rates in recognition memory for paintings and words

When old/new recognition memory is tested with equal numbers of studied and nonstudied items and no rewards or instructions that favour one response over the other, there is no obvious reason for response bias. In line with this, Canadian undergraduates have shown, on average, a neutral response bias when we tested them on recognition of common English words. By contrast, most subjects we have tested on recognition of richly detailed images have shown a conservative bias: they more often erred by missing a studied image than by judging a nonstudied image as studied. Here, in an effort to better understand these materials-based bias effects (MBBEs), we examined changes in hit and false alarm (FA) rates (and in sensitivity and bias) from the first to fourth quartile of a recognition memory test in eight experiments in which undergraduates studied words and/or images of paintings. Response bias for images tended to increase across quartiles, whereas bias for words showed no consistent pattern across quartiles. This pattern could be described as an increase in the MBBE over the course of the test, but the underlying patterns for hits and FAs are not easily reconciled with this interpretation. Hit rates decreased over the course of the test for both materials types, with that decline tending to be steeper for images than words. For words, FA rates tended to increase across quartiles, whereas for paintings FA rates did not increase across quartiles. We discuss implications of these findings for theoretical accounts of the MBBE.

Bilateral eye movements enhance the retrieval of episodic memories

Two experiments examining effects of eye movements on episodic memory retrieval are reported. Thirty seconds of horizontal saccadic eye movements (but not smooth pursuit or vertical eye movements) preceding testing resulted in selective enhancement of episodic memory retrieval for laboratory (Experiment 1) and everyday (Experiment 2) events. Eye movements had no effects on implicit memory. Eye movements were also associated with more conservative response biases relative to a no eye movement condition. Episodic memory improvement induced by bilateral eye movements is hypothesized to reflect enhanced interhemispheric interaction, which is associated with superior episodic memory (S. D. Christman & R. E. Propper, 2001). Implications for neuropsychological mechanisms underlying eye movement desensitization and reprocessing (F. Shapiro, 1989, 2001), a therapeutic technique for posttraumatic stress disorder, are discussed.