Response latency as an index of response strength during functional analyses of problem behavior.

The team ran regular functional analyses but added a twist. They timed how fast each response started instead of just counting how many happened.

They wanted to know if this speed score could stand in for the usual rate or percentage numbers when you track if treatment is working.

Latency mirrored the old metrics every time. When problem behavior got stronger, responses came faster. When treatment worked, responses slowed down.

The match was so close that you could swap the measures without losing the story of what the behavior was doing.

Griffith et al. (2021) also shrank FA sessions—five-minute blocks gave the same function as ten. Both studies show you can trim time without losing accuracy; latency just does it with a stopwatch instead of a shorter session.

Salzer et al. (2025) took FA to dogs and compared trial-based versus full formats. Their finding lines up here: quick micro-measures still reveal the true reinforcer, whether you count trials or time the first bark.

Jenkins et al. (1973) first proved latency tracks stimulus control even when the learner goofs. Matson et al. (2011) moves that lab trick into everyday FA and treatment checks.

You already carry a timer—your phone. Start it when the session begins and stop it at the first problem response. One number now tells you if the behavior is gaining or losing strength across conditions and across weeks of treatment. No extra sheets, no math, just speed.