Obstacle detection: A pilot study investigating the effects of lamp type, illuminance and age

A novel apparatus was used to examine the effect of light source, illuminance and observer’s age on the ability to detect obstacles in peripheral vision, simulating a raised paving slab under mesopic visual conditions. The data collected were used to determine the height of obstacles above the paving surface required for 50% detection. From these detection heights it was determined that: (1) obstacle detection was influenced by illuminance, the 50% detection height being lower at 20 lux than at 0.2 lux, (2) the young observers (60 years old) age groups, and (3) obstacle detection was affected by lamp type at 0.2 lux, with the 50% detection height decreasing as lamp S/P ratio increased, but at 2.0 and 20 lux there was no significant difference between the three test lamps