On the development and mechanics of delayed matching-to-sample performance.
Give DMTS at least one-hundred-fifty sessions before you call the score stable, especially with eight-second or longer delays.
01Research in Context
What this study did
The team ran a delayed matching-to-sample task for many sessions. They watched how accuracy changed when the delay grew from zero to sixteen seconds.
No diagnosis group is named, so we treat the data as a basic learning curve. The goal was to see how long steady performance takes to show up.
What they found
Accuracy jumped fast at short delays. Once the delay reached eight seconds or more, the curve flattened. It took about one-hundred-fifty sessions before scores stopped climbing.
Early wrong picks forecast later shifts in stimulus control. If you stop too soon, you may think the learner has poor memory when the curve is still rising.
How this fits with other research
McDougale et al. (2020) looked at how BCBAs set mastery rules. They found many pick low accuracy after only a few trials. Kangas et al. (2011) warns that this shortcut can hide true skill when delays are long.
Stinson et al. (2022) reviewed mobile momentary checks and saw huge accuracy swings. Their point is the same: measure long enough before you trust the number.
Sperandini et al. (2026) tracked IQ scores across years and saw some big jumps. Long runs of data, like the one-hundred-fifty DMTS sessions, help catch those late changes that short probes miss.
Why it matters
If you use DMTS to test working memory, keep the task alive for at least three months of daily trials before you write the score in a report. Short probes can label a learner as forgetful when the curve simply has not peaked yet.
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02At a glance
03Original abstract
Despite its frequent use to assess effects of environmental and pharmacological variables on short-term memory, little is known about the development of delayed matching-to-sample (DMTS) performance. This study was designed to examine the dimensions and dynamics of DMTS performance development over a long period of exposure to provide a more secure foundation for assessing stability in future research. Six pigeons were exposed to a DMTS task with variable delays for 300 sessions (i.e., 18,000 total trials; 3,600 trials per retention interval). Percent-correct and log-d measures used to quantify the development of conditional stimulus control under the procedure generally and at each of five retention intervals (0, 2, 4, 8 and 16-s) individually revealed that high levels of accuracy developed relatively quickly under the shorter retention intervals, but increases in accuracy under the longer retention intervals sometimes were not observed until 100-150 sessions had passed, with some still increasing at Session 300. Analyses of errors suggested that retention intervals induced biases by shifting control from the sample stimulus to control by position, something that was predicted by observed response biases during initial training. These results suggest that although it may require a great deal of exposure to DMTS prior to obtaining asymptotic steady state, quantification of model parameters may help predict trends when extended exposure is not feasible.
Journal of the experimental analysis of behavior, 2011 · doi:10.1901/jeab.2011.95-221