Impact of Dual-Coding and Sensory Coupling on Vigilance Decrement: Criterion Shift or Sensitivity Loss?

The study investigated whether vigilance performance improves when tactile stimuli are dual-coded with visual or auditory signals, compared to unimodal conditions. Prior studies investigated visual-audio dual coding, whereas dual coding including tactile information has not been examined. One hundred participants completed a 40-min vigilance task under tactile-only, visual-only, audio-only, visual-tactile, or audio-tactile conditions. Participants pressed the spacebar when the critical stimulus (shorter duration) occurred and withheld responses when the neutral stimulus (longer duration) occurred. Results showed a vigilance decrement in all conditions, with decreases in proportion of correct detections and sensitivity, and increases in response bias, reaction time and false alarms, during the course of the vigil. Dual-coded conditions showed higher sensitivity and proportion of correct detections compared to unimodal conditions, and the audio-tactile condition yielded the best performance. These results suggest that dual coding with closely coupled (audio-tactile) modalities improves signal salience, especially in tasks requiring duration discrimination.