For most people, the reactionary gap is ____ to _____ of a second.

• A. 1/4 to 1/2 of a second
• B. 1/2 to 3/4 of a second
• C. 1 to 2 seconds
• D. 0.1 to 0.2 seconds

Answer: (B)

The reactionary gap is the time between when you notice a hazard and when you begin to take action, such as applying the brakes. For most people, that time falls roughly in the range of 0.5 to 0.75 seconds. This interval reflects the real-world speed of perception, decision-making, and initiating a physical response. Understanding it helps you gauge a safe following distance, since the distance you cover in that half- to three-quarters-second window adds to braking distance. For example, at 60 mph you travel about 88 feet per second, so a 0.5 to 0.75 second reaction results in roughly 44 to 66 feet of travel before you start braking. Shorter times underestimate typical human reaction, while longer times are less representative for normal driving; the 0.5–0.75 second range aligns with how drivers commonly respond to hazards. Fatigue, stimulant use, distraction, or age can widen this gap, further affecting stopping distance.