Adjusting-Amount Procedure with Daily Delay Changes
Objective: To measure discounting of reinforcer value by delay in rats using an adjusting-amount procedure, determining indifference points where rats choose immediate and delayed water with equal frequency
Gather these items before starting the experiment. Check off items as you prepare.
Equipment1
not specified • not specified • not specified • not specified
Materials1
not specified • not specified • not specified • not specified
Software1
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Protocol Steps
Present choice between immediate and delayed water
Rats are presented with a choice between a varying amount of immediate water and a fixed amount of water delivered after a delay
Note: The amount of immediate water is systematically adjusted based on previous choices
View evidence from paper
“Eight rats chose between a varying amount of immediate water and a fixed amount of water given after a delay. The amount of immediate water was systematically adjusted as a function of the rats' previous choices”
Adjust immediate water amount based on choices
The amount of immediate water is adjusted systematically to determine the indifference point where rats choose the immediate and delayed amounts with equal frequency
Note: Indifference points are reached quickly under daily delay changes
View evidence from paper
“the rats reached indifference points within the first 30 trials of each 60-trial session”
Vary delay to fixed reinforcer daily
In Experiment 1, the delay to the fixed reinforcer is changed daily across different delay values
Note: Five delay conditions tested: 0, 2, 4, 8, or 16 seconds
View evidence from paper
“the effects of daily changes in the delay to the fixed reinforcer (100 microliters of water delivered after 0, 2, 4, 8, or 16 s) were tested”
Record indifference point
The amount of immediate water at the indifference point is recorded and used to estimate the value of the delayed amount of water
Note: Indifference point is where rat chooses immediate and delayed amounts with equal frequency
View evidence from paper
“This procedure was used to determine the indifference point at which each rat chose the immediate amount and the delayed amount with equal frequency. The amount of immediate water at this indifference point was used to estimate the value of the delayed amount of water”