Successive incrementing non‐matching‐to‐samples in rats: An automated version of the odor span task
An automated nose-poke odor span task gives reliable working-memory data in rats with minimal staff time.
01Research in Context
What this study did
The team built an automated odor span task for rats. The chamber released new smells one at a time.
Each trial asked the rat to pick the scent it had NOT smelled before. Correct nose pokes earned food.
The computer kept adding one more odor every block, so the list to remember kept growing.
What they found
Rats chose the new smell almost every time when the list was short.
Memory dropped only after longer waits between odors.
The machine version worked as well as older hand-run setups.
How this fits with other research
Gurley (2019) showed you can build a working operant box for under $200 with a Raspberry Pi. Galizio et al. (2020) took that cheap hardware and added an olfactometer to run the span task.
Glynn (1990) used the same lab and same rat model to test auditory instead of olfactory memory. Both studies found quick learning, proving the preparation is solid across senses.
Witts et al. (2024) also chase automated assessment, but rank how bad stimuli feel rather than how many items animals recall. Together the papers push toward faster, tech-based animal tests.
Why it matters
If you study memory or need a quick cognitive screen, an automated span task gives clean data with almost no experimenter time. You can build the rig for pocket money and run dozens of sessions a day. Swap odors for pictures or sounds and the same code works with kids or pigeons. Try it next time you need a scalable working-memory measure.
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02At a glance
03Original abstract
The odor span task is a procedure frequently used to study remembering of multiple stimuli in rodents. A large arena is used and odor stimuli are presented using scented cups. Selection of each odor is reinforced when first presented, but not on subsequent presentations; correct selections depend on remembering which stimuli were previously presented. The use of an arena setting with manual stimulus presentation makes the odor span task labor-intensive and limits experimental control; thus, an automated version of the task would be of value. The present study used an operant chamber equipped with an olfactometer and trained rats using successive conditional discrimination procedures under an incrementing non-matching-to-samples contingency. High rates of responding developed to odor stimuli when they were session-novel with low rates of responding to subsequent presentations of that odor. Additional experiments assessed variations of the procedure to determine the role of the frequency of odor presentation and the retention interval separating sample and comparison. Discrimination was impaired with long retention intervals suggesting the importance of this variable. These findings confirmed that rats differentiate between stimuli that are session-novel and those previously encountered and support the use of an automated procedure as an alternative to the odor span task.
Journal of the Experimental Analysis of Behavior, 2020 · doi:10.1002/jeab.619