When Auditory and Visual Signal Processing Conflict: Cross-Modal Interference in Extended Work Periods

Auditory and visual stimuli presented at intervals of about 300 m sec often produce miss errors in one or the other channel, which result from a bottleneck in a neural circuit associated with executive memory. The present study examined the possibility that cross-modal interference could carry over to performance units that transpire over 3 min or longer. An N-back task performed by 113 undergraduates with simultaneous auditory and visual stimuli was organised into 1-min blocks of 20 trials in 2-back and 3-back conditions. Results showed that impairment of visual processing was more frequent than impairment of auditory processing under conditions of fatigue. A substantial number of person blocks showed no such interference, however. Bottlenecks during early stages of processing may have more extensive effects on later processing than previously recognised. Further research should consider perceptual cycling in longer term tasks involving complex stimuli

An Oscillating Cortical Model of Auditory Attention and Electrophysiology

We present preliminary work on a computational neural network model of both behavioral and electrophysiological data from perception to response in an auditory discrimination experiment of Alain and Woods showing the EEG-ERP effects of attention and auditory stream clustering. The architecture models the N1/P2 and N2/P3b sequence of evoked potentials as variations in cortical excitability (gain) due to thalamic inputs which control a sensory/motor processing cycle. Gamma band oscillatory associative memory attractor activations occur on the negative peaks followed by resets on the positive peaks. A transient gamma burst on stimulus arrival in the early N1 stage determines preattentive stream clustering by synchronization of separate activity at different frequencies. Frontal attentional control signals in the gamma band selectively synchronize with the target stream activity to apply a gain enchancing bias that affects all inputs captured by that stream. Later gamma power enhancement a..