Final answer:
The EMG artifact associated with photic stimulation is known as a Photomyogenic artifact. This artifact is produced by synchronous muscular activity that occurs during photic stimulation and is important to identify correctly in EMG readings.
Step-by-step explanation:
The EMG artifact that is time-locked with photic stimulation is called Photomyogenic artifact. An EMG, or electromyography, measures the electrical activity of muscles at rest and during contraction. Photic stimulation involves exposing subjects to varying frequencies of flashing lights; if there is synchronous muscular activity with this visual stimulus, it generates artifacts on the EMG reading that could be mistaken for abnormal brain activity. Therefore, it's critical to recognize such artifacts to avoid misinterpreting them as indicative of neurological disorders.