Impaired perception of temporal order in auditory extinction

Area of Science:

• Neuroscience
• Cognitive Psychology
• Auditory Perception

Background:

• Patients with extinction often show spatial attention bias towards the ipsilesional side.
• The law of 'prior entry' suggests ipsilesional events are perceived earlier than synchronous contralesional stimuli.
• Previous studies documented delays in awareness for contralesional visual and tactile stimuli in extinction patients.

Purpose of the Study:

• To investigate if a 'prior entry' bias occurs in the auditory modality for patients with extinction.
• To determine if the delay in awareness for contralesional events is sensory modality-independent.

Main Methods:

• Auditory extinction patients were presented with two acoustic events, one to each ear.
• Participants judged the simultaneity of the auditory events.
• The lead time of the contralesional sound was manipulated to determine the point of perceived simultaneity.

Main Results:

• Patients with auditory extinction perceived sounds as simultaneous when the contralesional sound led by approximately 270 ms.
• This auditory asynchrony magnitude was comparable to previously reported visual modality findings.
• The results indicate a significant delay in awareness for contralesional auditory events.

Conclusions:

• A 'prior entry' bias is present in the auditory modality for patients with extinction.
• The pathological delay of awareness for contralesional events appears to be independent of the sensory modality.
• Findings support a generalized deficit in spatial attention processing in extinction.