An individual difference influencing the extent to which an individual is high on sensory-processing sensitivity. Highly sensitive people are often aware of subtleties in their surrounding but more easily overwhelmed when they have been out in a highly stimulating environment for too long.
Benham, G. (2006). The highly sensitive person: Stress and physical symptom reports. Personality and Individual Differences, 40(7), 1433-1440.
Aron, E.N. (2003). The highly sensitive person: How to thrive when the world overwhelms you. London: Harper Collins.