Quinine pellets as an inferior good and a Giffen good in rats.
Cutting overall reinforcement availability can make even low-quality options more attractive, so monitor client preference shifts when you thin schedules.
01Research in Context
What this study did
Researchers let rats pick between two levers. One lever gave regular food pellets. The other gave pellets laced with bitter quinine.
The team then cut the total number of trials. Fewer chances to eat made the rats choose the bitter pellets more often.
What they found
When pellets got scarce, rats upped their intake of the nasty-tasting ones. The bad pellets acted like an 'inferior good' and a 'Giffen good' at the same time.
In plain words: raising the 'cost' of eating made the poor-option more attractive, not less.
How this fits with other research
Galuska et al. (2017) saw the same pattern. When rats shifted from rich to lean pellet schedules, they drank more sucrose or water on the side. Both studies show scarcity boosts alternate reinforcer use.
Ballard et al. (1975) reported it first. Lower reinforcement rate increased post-pellet water drinking. Bailey et al. (1990) now proves the effect holds even when the alternate 'reinforcer' tastes awful.
Higgins et al. (1992) tightened the screw further. Fewer total trials made rats wait longer for bigger pellet rewards. Together the papers say: cut income and animals change both quality and delay choices.
Why it matters
Your client's world can shrink too. Fewer teaching trials, shorter sessions, or thinner schedules all drop 'reinforcement income.' When that happens, lower-quality reinforcers may suddenly look better. Watch for kids picking previously rejected toys, foods, or activities after you thin a schedule. Track these shifts; they signal the economy of reinforcement is changing.
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Join Free →Count how often your client approaches each available reinforcer after you reduce trial number; keep the tally for one session to spot any new 'inferior' favorites.
02At a glance
03Original abstract
In Experiment 1, 4 rats earned their daily food ration by choosing between two levers. One lever delivered two regular and one quinine-adulterated food pellets, and the other delivered two regular and four quinine pellets. A 20-s intertrial interval separated successive choices. Sessions began with 10 forced trials during which only one lever, selected with p = .5 and cued by a light above it, could deliver its reinforcer. Forced trials were followed by 30 or 150 trials, depending on the condition, during which choices to either lever could be reinforced. Over this range, absolute choice of the four-quinine, two-regular-pellet lever was inversely related to the number of free-choice trials, establishing this reinforcer as an inferior good. In Condition 1 of Experiment 2, the prior design was altered in two ways: (a) one lever delivered four quinine pellets, and the other lever delivered one standard pellet; and (b) sessions ended after 140 free-choice trials. When the number of free-choice trials was reduced to 100 (Condition 2), all 3 rats increased their preference for quinine pellets, confirming their status as an inferior good. In the next several conditions, the number of quinine pellets provided for selecting its associated lever was varied between three and four. Preference for the quinine-pellet alternative was inversely related to the number of pellets it provided, a result defining it as a Giffen good. These findings are not accommodated readily by extant choice models and complicate the search for a unitary model of choice.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-263