Generalization of free-operant avoidance behavior in pigeons.
Excitatory and inhibitory generalization gradients add together like simple numbers, giving you a clear map for fading stimulus control.
01Research in Context
What this study did
Four pigeons learned to avoid shock by pecking during a warning tone.
The birds then heard new tones that were close to or far from the trained sound.
Researchers tracked how much each bird pecked at every new pitch.
What they found
The birds made neat hills and valleys of pecking.
Strong responses near the warning tone and weak responses near the safe tone added up perfectly.
This matched Spence's old math idea that excitatory and inhibitory gradients stack like numbers.
How this fits with other research
BERRYMAELLIOTT et al. (1962) showed rats learn faster when the warning and safe sounds are far apart.
Thompson et al. (1974) used that same logic but proved the gradients actually sum together.
Ghosh et al. (2004) later found pigeons also generalize to blended pictures, showing the gradient idea works across senses.
Cicchetti et al. (2014) pushed further, showing pigeons can juggle four visual dimensions at once while still forming clean gradients.
Why it matters
When you teach a child to cross the street only on the walk signal, think of two overlapping hills.
One hill is 'cross now' and the other is 'wait.' Make the hills far apart at first, then bring them closer as the learner masters the skill.
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Join Free →Plot your S-D and S-delta on a line, then test two probe stimuli halfway between to see if the gradients sum as expected.
02At a glance
03Original abstract
Three groups of four pigeons, trained to press a treadle on a free-operant avoidance schedule, were given auditory discrimination training. Alternating 2-min components of avoidance and no shock were paired with either a tone or white noise. The pigeons were subsequently given two types of generalization tests, with and without avoidable shocks scheduled. Two of the groups, trained interdimensionally, produced excitatory and inhibitory generalization gradients along the tone frequency dimension. A predicted post-discrimination gradient was computed from the algebraic summation of these gradients of excitation and inhibition. The predicted gradient was compared with the actual post-discrimination gradient obtained from the third group of pigeons that had been given intradimensional discrimination training on the tone frequency dimension. The predicted postdiscrimination gradient agreed in shape with the empirical postdiscrimination gradient. The results in general support Spence's (1937) gradient interaction theory.
Journal of the experimental analysis of behavior, 1974 · doi:10.1901/jeab.1974.21-75