Blocking a selective association in pigeons.
A prior cue can block a new one even in pigeons, so built-in preferences are not fixed.
01Research in Context
What this study did
Webb et al. (1999) worked with pigeons in a lab.
They copied the exact pre-training rats had received in earlier blocking studies.
The goal was to see if pigeons would also block a selective link between food and a light.
What they found
The birds learned to ignore the light when it was added after an old signal.
This blocking effect matched what rats had shown.
It proved the same rule can override hard-wired preferences in two very different species.
How this fits with other research
Lerner et al. (2012) also repeated an earlier animal study, but they found no nicotine benefit for pigeon memory.
Together the two papers show that replications in pigeons sometimes confirm old rules and sometimes cancel them.
Campos et al. (2014) later showed pigeons can form equivalence without identity training, so birds are capable of flexible learning when the method is right.
Why it matters
You can override built-in biases if you first give a reliable cue.
Use blocking when you want a client to ignore a flashy but useless stimulus.
Start with a proven signal, then add the new one; the learner will tune it out just like the pigeons did.
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02At a glance
03Original abstract
Experiment 1 demonstrated for the first time a stimulus-reinforcer interaction in pigeons trained with free-operant multiple schedules of reinforcement. Pigeons that treadle pressed in the presence of a tone-light (TL) compound for food exhibited primarily visual stimulus control on a stimulus-element test, whereas pigeons that avoided shock in TL exhibited auditory control. In Experiment 2, this selective association was blocked in pigeons pretrained with the biologically contingency-disadvantage element of the compound (i.e., tone-food or light-shock) before TL training. When this pretraining preceded compound-stimulus training, control was now auditory in pigeons that treadle pressed for food and was visual in pigeons that avoided shock. Previous attempts at blocking this selective association were unsuccessful in pigeons (LoLordo, Jacobs, & Foree, 1982) but were successful in rats (Schindler & Weiss, 1985). Experiment 2 established that selective associations can be blocked in pigeons when the procedures that were effective with rats were systematically replicated. These results further demonstrate the cross-species generality of an associative attentional mechanism involving a biological constraint on learning in species with different dominant sensory systems.
Journal of the experimental analysis of behavior, 1999 · doi:10.1901/jeab.1999.71-13