Simultaneity Window

[Concepts in Sensorimotor Research]

Simultaneity Window (SW) refers to a temporal window within which the brain perceives stimuli from different sensory modalities as occurring simultaneously. It represents the temporal range over which the brain integrates sensory inputs from different modalities into a coherent percept.

If stimuli from different modalities fall within the SW, they are likely to be perceptually integrated, whereas if they fall outside the SW, they may be perceived as separate events.

Commonly used research tasks to measure SW

• Temporal Order Judgment (TOJ): participants are presented with 2 stimuli, one in each sensory modality (e.g., a flash of light and a beep), and they have to determine the order in which the stimuli occurred.
• Simultaneity Judgment (SJ): Participants are presented with 2 stimuli, from different modalities, and they have to judge whether the stimuli were perceived as simultaneous or not.
• Temporal Alignment Task: Participants are presented with a stimulus in one modality and have to adjust the timing of a stimulus in the other modality until it is perceived as synchronous with the first stimulus. This helps in determining the temporal window of integration.
• Temporal Recalibration Task: Participants are exposed to a consistent asynchrony between stimuli from different modalities over a period of time. Following this exposure, their perception of simultaneity is tested to see if it has been recalibrated.

The perception of simultaneity can vary across individuals and is influenced by various factors such as attention, age, disability, the specific sensory modalities involved, and distance of stimuli (as determined by, say the PPS).