Where Association Ends. A Review of Associative Learning in Invertebrates,Plants and Protista,and a Reflection on Its Limits

Loy, I. and Carnero-Sierra, Susana and Acebes, F. and Muñiz-Moreno, J. and Muñiz-Diez, C. and Sánchez-González, Jose Carlos (2021) Where Association Ends. A Review of Associative Learning in Invertebrates,Plants and Protista,and a Reflection on Its Limits. Journal of Experimental Psychology: Animal Learning and Cognition, 47 (3). pp. 234-251. ISSN 2329-8456

Abstract

Since the beginning of the 21st century, the Minimal Cognition approach has emerged vigorously,focusing on the study of the adaptive behavior of the simplest organisms, including bacteria, assuming that they are sentient and information-processing entities. Although Minimal Cognition has occasionally used Pavlovian methods to try to demonstrate Associative Learning, neither the Psychology of Learning nor the Comparative Psychology traditions are prominent in the movement. However, the Psychology of Learning approach, with its highly sophisticated experimental designs, has done a great deal of research on Associative Learning in animals and carried out several studies on plants and unicellular organisms. The present work offers a comprehensive review of these experimental results, among invertebrates,plants and unicellular organisms (paramecia and the amoeba Physarum policephalum) showing that, while there are increasing instances of Associative Learning in many invertebrate phyla (and also many phyla with no data) there is no adequate evidence of it in unicellular protists (despite more than a century of experiments with paramecia and amoeba) or in plants (despite recent results that so claim).We then consider the alternative offered by Minimal Cognition and suggest some complementary ideas,from a Comparative Developmental Psychology approach, which we call “Minimal Development.”