Discrimination learning and extinction in Paramecia (P-caudatum)
ABSTRACT Prior attempts to condition a one-celled organism, paramecium, by either classical or instrumental procedures have yielded both positive and negative results. As the results of those studies may be subject to several interpretations other than one indicating learning, it was decided to use a more traditional technique for the present study. This experiment was designed to assess whether aversive electric shock could be used to train paramecia on a brightness discrimination task, a procedure that has been used in animal learning research. The results indicated that such learning may have occurred.
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ABSTRACT: Extinction and its related phenomena are central to the study and development of associative learning theory. For a better understanding of the processes involved in extinction, it is important to know how general these phenomena are in different species. Extensive evidence of extinction in invertebrate species would be necessary in order to test the generality of its current theoretical and physiological accounts. We carried out three sets of experiments using terrestrial snails Helix aspersa. The repeated nonreinforced presentation of the conditioned stimulus (CS) resulted in a decrease in responding (extinction); the introduction of a delay between the extinction of a CS and its test produced an increase in responding (spontaneous recovery); and re-exposure to the unconditioned stimulus after extinction also led to an increase in responding (reinstatement). The results are discussed in relation to current interference theories of extinction.Animal Behaviour 06/2014; 92:75–83. DOI:10.1016/j.anbehav.2014.03.023
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ABSTRACT: In order to introduce protists to philosophers, we outline the diversity, classification, and evolutionary importance of these eukaryotic microorganisms. We argue that an evolutionary understanding of protists is crucial for understanding eukaryotes in general. More specifically, evolutionary protistology shows how the emphasis on understanding evolutionary phenomena through a phylogeny-based comparative approach constrains and underpins any more abstract account of why certain organismal features evolved in the early history of eukaryotes. We focus on three crucial episodes of this history: the origins of multicellularity, the origin of sex, and the origin of the eukaryote cell. Despite ongoing uncertainty about where the root of the eukaryote tree lies, and residual questions about the precise endosymbioses that have produced a diversity of photosynthesizing eukaryotes, evolutionary protistology has illuminated with considerable clarity many aspects of protist evolution. Our main message in light of evolutionary protistology is that these ‘other eukaryotes’ are in fact the organisms through which the rest of the eukaryotes should be understood.Biology and Philosophy 03/2012; 28(2). DOI:10.1007/s10539-012-9354-y