A mild degree of awareness oscillation is normal, and it becomes abnormal at the point when the rate of oscillation is so rapid that the illusion of simultaneous awareness is created. Illusion of simultaneous awareness is the sensation that one is truly aware of more than one mode of awareness at once, instead of oscillating rapidly between experiences. This experience may or may not be believed by the person to be a real experience. Examples include feeling that one is processing the sight of a cat and the sound of a miaow at the same time, feeling that one is processing two different people's voices and words at the same time, or feeling that one is processing self-awareness and awareness of other people at the same time. If this illusion is believed, then delusional or transient-delusional may be specified, depending on the duration and quality of the delusion.
Sensory overload can also result in a similar experience to illusion of simultaneous awareness .
However, unlike the illusion of simultaneous awareness , sensory overload has a quality of confusion and loss of awareness. Therefore, if all symptoms are experienced during sensory overload, the awareness component is lacking. However, if symptoms are sometimes experienced without direct association to sensory overload, diagnosis is still possible. The abnormal awareness oscillation and illusion of simultaneous awareness can cause marked distress, especially in people who do not experience these symptoms constantly. In people for whom it does not cause marked distress, it can cause deficiencies in social interaction, particularly with people who do not have Pseudo-Simultaneous Awareness Disorder.