Feature- versus rule-based generalization in rats, pigeons and humans

Abstract

Humans can spontaneously create rules that allow them to efficiently generalize what they have learned to novel situations. An enduring question is whether rule-based generalization is uniquely human or whether other animals can also abstract rules and apply them to novel situations. In recent years, there have been a number of high-profile claims that animals such as rats can learn rules. Most of those claims are quite weak because it is possible to demonstrate that simple associative systems (which do not learn rules) can account for the behavior in those tasks. Using a procedure that allows us to clearly distinguish feature-based from rule-based generalization (the Shanks–Darby procedure), we demonstrate that adult humans show rule-based generalization in this task, while generalization in rats and pigeons was based on featural overlap between stimuli. In brief, when learning that a stimulus made of two components (“AB”) predicts a different outcome than its elements (“A” and “B”), people spontaneously abstract an opposites rule and apply it to new stimuli (e.g., knowing that “C” and “D” predict one outcome, they will predict that “CD” predicts the opposite outcome). Rats and pigeons show the reverse behavior—they generalize what they have learned, but on the basis of similarity (e.g., “CD” is similar to “C” and “D”, so the same outcome is predicted for the compound stimulus as for the components). Genuinely rule-based behavior is observed in humans, but not in rats and pigeons, in the current procedure. Electronic supplementary materialThe online version of this article (doi:10.1007/s10071-015-0895-8) contains supplementary material, which is available to authorized users.

Three Ways That Non-associative Knowledge May Affect Associative Learning Processes

“…test trials and thus influence the outcome expectation. Maes et al (2015) have shown that this pattern of abstract rule generalization is absent from the behavior of rats and pigeons, which appear to generalize mainly in ways consistent with associative learning principles. Cobos et al (2016) showed the same is true for humans when using a cued-response priming task, whereas verbal ratings were consistent with rule-based generalization.…”

A stimulus-location effect in contingency-governed, but not rule-based, discrimination learning.

“…Maes et al, 2015;Smith, Ashby, Berg et al, 2011;Wills, Lea, Leaver et al, 2009), and the second aim of the present paper is to add to this strand of literature. Many differences between learning in humans and non-human learning can be attributed to the human tendency to formulate verbal rules to guide behaviour (Skinner, 1969).…”

“…The present paper reports a further case of a minor procedural change producing a major difference in rate of acquisition, again in a conditional discrimination procedure. The phenomenon was noted, but not explored systematically, in the course of pilot work with pigeons for experiments reported by Maes, De Filippo, Inkster et al (2015). The principal aim of the present paper was to investigate the phenomenon in a controlled experiment.…”

Bending rules: the shape of the perceptual generalisation gradient is sensitive to inference rules

“…Although rule learning is common in humans (Maes et al, 2015), it is still unclear how such mechanism may account for phenomena like the perceptual generalisation gradient. To obviate this lacuna, we theorise that people apply the inference rule "the more stimuli look alike, the higher the chance that they will have the same outcome".…”