The effects of session length on demand functions generated using FR schedules.
Compare equal time windows, not total session length, when you judge demand or mastery.
01Research in Context
What this study did
Flood et al. (2011) worked with hens in a small lab space.
The birds pecked a key under fixed-ratio schedules.
Some sessions ended after 5 min, others after 60 min.
The team tracked how many pecks happened and how long the birds paused.
What they found
Short sessions made the hens peck faster and pause less.
Demand curves looked steeper at first.
When the team only looked at the first 5 min of every session, the difference vanished.
Session length itself, not time inside the session, changed the numbers.
How this fits with other research
Mellott et al. (2023) took the idea into a classroom.
Kids liked mixed-length work periods and finished more math sheets.
Both studies show the same rule: changing duration changes performance.
Mace et al. (1990) warned that short samples can miss rare behaviors.
Mary’s team adds a twist: short samples can also over-count common behaviors.
Together they tell us to match session length to the question we are asking.
Why it matters
If you run 10-min probes to check skill mastery, know that rates may look higher than they would in a 30-min class period.
Before you say a learner has “mastered” a task, test for longer or compare equal time windows.
This guards against false positives and keeps your data honest.
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02At a glance
03Original abstract
In comparing open and closed economies, researchers often arrange shorter sessions under the former condition than under the latter. Several studies indicate that session length per se can affect performance and there are some data that indicate that this variable can influence demand functions. To provide further data, the present study exposed domestic hens to series of increasing fixed-ratio schedules with the length of the open-economy sessions varied over 10, 40, 60, and 120 min. Session time affected the total-session response rates and pause lengths. The shortest session gave the greatest response rates and shortest pauses and the longest gave the lowest response rates and longest pauses. The total-session demand functions also changed with session length: The shortest session gave steeper initial slopes (i.e., the functions were more elastic at small ratios) and smaller rates of change of elasticity than the longest session. Response rates, pauses, and demand functions were, however, similar for equivalent periods of responding taken from within sessions of different overall lengths (e.g., total-session data for 10-min sessions and the data for the first 10 min of 120-min sessions). These findings suggest that differences in session length can confound the results of studies comparing open and closed economies when those economies are arranged in sessions that differ substantially in length, hence data for equivalent-length periods of responding, rather than total-session data, should be of primary interest under these conditions.
Journal of the experimental analysis of behavior, 2011 · doi:10.1901/jeab.2011.95-289