12 Invertebrate Cognition: Nonelemental Learning beyond Simple Conditioning

Cognitive science has become fashionable in recent years: A simple search for the word “cognition” in scientific databases will show the extent to which the scientific literature has incorporated a term that 10 years ago was rarely used. From psychological and philosophical studies to neurobiological studies, from modeling and robotics to ethological studies, from ecology to molecular biology, the word cognition can be found almost everywhere, because cognitive science has acquired a new dimension that reflects our growing interest in essential problems like consciousness, brain processing, and the emergence of thinking. Despite this diversity and increasing interest, a general definition for the term cognition remains elusive, probably because the approaches that characterize cognitive studies are diverse and still looking for a synthesis. Indeed, the term cognition may encompass concepts as diverse as human thinking and intelligence, functions leading to the acquisition and generation of meaning in explicit form, and basic perceptual processes (Wullimann and Roth 2001). Broader definitions have been proposed to include processes of acquisition and manipulation of information, attention, perception, decision making, learning, and memory (Shettleworth 1998Shettleworth 2001). In this chapter, I survey the evidence that such concepts can be applied in invertebrates. To provide an operational framework for this survey, I confine the use of the term cognition to complex forms of associative learning. In particular, because the term “complex” is also meaningless if it is not referred to a certain level of simplicity, I focus on nonelemental forms of associative learning —learning forms in which simple,...