Source Paper
Information, certainty, and learning
Harris JA, Gallistel CR
eLife • 2026
Pavlovian Conditioning with Variable CS-US Intervals
Objective: To examine how variable CS-US intervals affect Pavlovian conditioning acquisition and responding patterns using different C/T ratios
This is a Pavlovian Conditioning with Variable CS-US Intervals protocol using Rat as the model organism. The procedure involves 10 procedural steps, 4 equipment items, 2 materials. Extracted from a 2026 paper published in eLife.
Model and subjects
Rat • female albino Sprague Dawley rats • female • 8–10 weeks of age • 176
Study window
~3 day study window
Core workflow
Housing and food restriction • Daily feeding schedule • Group allocation
Primary readouts
- Trials to acquisition using cumulative response rate analysis
- Trials to acquisition using nDKL statistic at different thresholds
- Terminal response rate over last 5 conditioning sessions
- Response rate components: latency to first response, mean duration of each response, interval between responses
Key equipment and reagents
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Protocol Steps
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Housing and food restriction
House rats in groups of 4 and implement food restriction 3 days before experiment
View evidence from paper
“Three days before commencing the experiment, they were placed on a restricted food schedule”
Daily feeding schedule
Feed rats daily ration of dry chow equal to 5% of total tub weight 30 minutes after training
View evidence from paper
“half an hour after the end of the daily training session, each tub of rats received a ration equal to 5% of the total weight”
Group allocation
Randomly allocate each tub of four rats to one of 14 experimental groups with different C/T ratios
View evidence from paper
“Each tub of four rats was randomly allocated to one of the 14 groups shown in Table 1”
Variable CS-US interval setup
Set CS-US intervals to vary trial-to-trial according to uniform distribution centered on group-specific T value
View evidence from paper
“the CS-US interval varied from trial-to-trial according to a uniform distribution centred on the value of T”
CS-US interval range
Program intervals to range from minimum of 2s to maximum of 2 × T-2s for each group
View evidence from paper
“the interval varied from a minimum of 2 s to a maximum of 2x T –2 s”
Inter-trial interval setup
Set ITI to vary trial-to-trial as uniform distribution with minimum of 15s
View evidence from paper
“The ITI in each group also varied from trial-to-trial as a uniform distribution with a minimum of 15 s”
Training parameters for Groups 1-11
Conduct 10 trials per session for groups with C/T ratios from 1.5 to 72
View evidence from paper
“For the first 11 groups (those with ratios from 1.5 to 72), there were 10 trials per session”
Training parameters for Groups 12-14
Conduct 3 trials per session for groups with C/T ratios of 110, 180, and 300
View evidence from paper
“for the remaining three groups (with C / T ratios of 110, 180, and 300), each session contained only three trials”
Daily training schedule
Train all groups with one session per day for total of 42 sessions
View evidence from paper
“All groups were trained with one session per day for a total of 42 sessions”
Response recording
Record photo-beam interruptions during each CS and during 10s period before CS onset
View evidence from paper
“Photo-beam interruptions by entry into the magazine were recorded during each CS and each ITI (recorded during the 10 s period immediately before CS onset)”