| Driving skill (reference #) | Impairment
Threshold |
choice reaction time (2)
 Time to make response choice - braking, steering, sound horn. | .03 |
choice reaction time errors (3)
Subject makes errors in selecting the appropriate response from a number of options available. | .05 |
concentrated attention (9)
Ability to focus on roadway and maintain vigilence & forward gaze. | .07 |
| visual reaction time (12,13) | .04 |
response to central stimuli (14)
Impaired response to stimulus within acute field of vision. | .04 |
visual search (15,24)
Ability to maintain searching pattern for objects on or about the roadway. | .05 |
visual recognition (15)
Ability to recognize objects after they have been perceived. | .07 |
interpretation of signals (16)
Ability of the operator to interpret brake lights, traffic signals, etc. is impaired even though the operator perceives the signal. | .05 |
comprehension (41)
Subject cannot accurately comprehend what has been perceived, and may misinterpret stimulus or be unable to process information. | .05 |
visual information processing (17)
Recognition and decision-making ability, using visual information. | .06 |
