If the inter-flash interval is increased beyond 100 ms, summation will occur?

If the inter-flash interval is increased beyond 100 ms, summation will occur?

• A. Yes
• B. No
• C. Only if larger arcs
• D. Only if shorter arcs

Answer: (B)

Temporal summation occurs when successive visual stimuli fall within a short time window, so their neural responses overlap and add together. If two flashes come close in time, the response from the first is still present when the second arrives, leading to a larger combined signal. But when the inter-flash interval is increased beyond about 100 ms, the first response has largely decayed before the second flash occurs, so there’s little or no overlap and no summation. So, increasing the interval beyond 100 ms prevents summation. The other phrasing about arcs isn’t relevant to this temporal effect.

Temporal summation occurs when successive visual stimuli fall within a short time window, so their neural responses overlap and add together. If two flashes come close in time, the response from the first is still present when the second arrives, leading to a larger combined signal. But when the inter-flash interval is increased beyond about 100 ms, the first response has largely decayed before the second flash occurs, so there’s little or no overlap and no summation. So, increasing the interval beyond 100 ms prevents summation. The other phrasing about arcs isn’t relevant to this temporal effect.