A new method of appetitive classical conditioning has the great economy of using laboratory rats and tongue-licking, a short-latency response. Tests for effect of drive on learning were carried down to the theoretically crucial level of zero relevant drive, with adequate exposure to the goal substance. When rats were classically conditioned under 4 levels of thirst drive, high drive Ss learned better than moderate drive ones, who learned better than satiated and supersatiated Ss which showed no appreciable learning. When drives were equalized by testing Vz of each group under high drive and Vz when satiated, only rats conditioned under high or medium drive showed evidence of learning, such evidence being clear-cut for only those tested under high drive.There is considerable theoretical controversy over the role of drive in learning and the experimental data (e.g., Kimble, 1961, pp. 414-415) are far from clear-cut. Some of this confusion comes from certain theoretical misunderstandings, and some from technical difficulties in collecting the data under the crucial condition of zero appetitive drive.As Spence (1956) has so clearly pointed out, one cannot expect any simple effect of drive on learning in many complex situations involving conflicting response tendencies. Although increased drive may strengthen all of the tendencies, if those responsible for errors are strengthened
Twenty planaria of each of two species were run in a light-dark apparatus. In addition to morphological differences between the two species, there were found to be highly significant differences between the species on the percentage of time spent in the light. Two measures were used with parallel results. Problem The report by Thompson & McConnell (1955) of classical conditioning in the planarian has led to wide interest in the behavior of this primitive invertebrate. The possibility of the demonstration of learning in a relatively simple animal creates excitement because of the possibility that new techniques of observation may permit the analysis ofthe structural or chemical changes involved in learning (Jensen, 1964). The usual conditioning procedure for planaria involves a light as CS and a shock as US. But Halas et al. (1961, 1962) report that light and shock produce behaviors of a similar topography in the planarian (cf Walter, 1907). The present experiment was performed after the authors noticed, while attempting to replicate Thompson & McConnell, that different species of planaria respond differently to light. The species of plan,aria were compared on the amount of time spent in the dark half of a light-dark apparatus. In addition, rate of swimming, morphology and clinging behavior were observed. Method Dugesia tigrina were obtained from the Connecticut Valley Biological Supply Company. The Dugesiadorotocephala were obtained from the General Biological Supply Company. Twenty worms of each species were chosen on the basis of size and appearance. Normal appearing, healthy worms of about 1.2 to 1.7 cm in length were used. In general, the Dugesiadorotocephala are larger at maturity than Dugesia tigrina and therefore size matching may result in a different maturity level between species, i. e., the Dugesia tigrina may have been less mature animals. We did not control this factor. The test apparatus was a solid plexiglass block which contained four V-shaped grooves, 1/2 in deep and 4 in long. The grooves were filled with spring water. Half of each groove was shielded from a 16-w fluorescent light bulb suspended 18 in above the block. No attempt was made to prevent light diffusion through the block.
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