A within-subject between-apparatus comparison of impulsive choice: T-maze and two-lever chamber.
The T-maze gives cleaner, more patient choices than the two-lever box when you measure impulsive choice in rats.
01Research in Context
What this study did
The team ran the same rats through two different setups.
One day the rats chose in a T-maze: run left for one pellet now or right for four pellets later.
Another day the same rats chose in a standard box with two levers: press the left lever for one pellet now or the right lever for four pellets later.
Delays went up and down so the researchers could see when each rat switched from patient to impulsive.
What they found
In the T-maze the rats waited for the big reward more often and their choices were steadier.
In the two-lever box the same rats took the small immediate reward more often and their choices jumped around.
The pattern held no matter how the delays were arranged.
How this fits with other research
Baker et al. (2005) saw something similar in mice. When they added an extra lever that did nothing, some mouse strains learned the real lever more slowly.
More stuff in the box seems to clutter the signal for rodents.
Azrin et al. (1967) also tweaked rat chambers. They swapped floor grids for surface electrodes to get cleaner avoidance data.
Both papers show that small hardware changes can make behavior clearer or messier.
Together they warn us: before you trust your numbers, test the box itself.
Why it matters
If you study choice with humans, the room layout, screen size, or response pad can act like the second lever. Run a quick comparison first. Pick the setup that gives the clearest, most stable choices. You will save sessions and get truer baseline data.
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02At a glance
03Original abstract
Whereas intertemporal choice procedures are a common method for examining impulsive choice in nonhuman subjects, the apparatus used to implement this procedure varies across studies. The purpose of the present study was to compare impulsive choice between a two-lever chamber and a T-maze. In Experiment 1, rats chose between a smaller, immediate reinforcer and a larger, delayed reinforcer, first in a two-lever chamber and then in a T-maze. Delay to the larger reinforcer changed in an ascending and descending order (0-32 s) across sessions. Experiment 2 examined the same between-apparatus comparison but under steady-state conditions with the delay fixed at 32 s. In Experiment 1, choice for the larger, delayed reinforcer was generally higher in the T-maze than in the two-lever chamber. Similarly in Experiment 2, steady-state choice for the larger, delayed reinforcer was higher in the T-maze. Choice for the 32-s delayed reinforcer was also greater in Experiment 2 than in Experiment 1, suggesting that extended exposure to the delay is required for the T-maze to yield reliable impulsive choice data. While the reasons for the between-apparatus discrepancies are at present unknown, results from both experiments clearly demonstrate that the apparatus matters when assessing overall level and reliability of impulsive choice data.
Journal of the experimental analysis of behavior, 2015 · doi:10.1002/jeab.159