Between-subject PREE and within-subject reversed PREE in spaced-trial extinction with pigeons

Three experiments explored the partial reinforcement extinction effect (PREE; greater resistance to extinction after partial, rather than continuous, reinforcement training), in a spaced-trial situation with pigeons. Experiments 1 and 2 report conventional PREEs with 24-h intertrial intervals and between-subject designs. The corresponding outcome (food reinforcement or nonreinforcement) was delivered after satisfaction of a fixed-ratio 10 (Experiment 1) or a fixed-ratio 1 (Experiment 2). Experiment 3 reports a reversed PREE in a within-subject design with a fixed-ratio 10 requirement. Extinction occurred faster for the response paired with 50% partial reinforcement than for the response paired with continuous reinforcement. A third response paired with a small reinforcer (1 pellet/trial) in 100% of the trials extinguished faster than a response paired with a large reinforcer (15 pellets/trial). These results are discussed in the context of spaced-trial instrumental performance (key pecking and running), in pigeons.     

How do I love thee? Let me count the Js: implicit egotism and interpersonal attraction

From the perspective of implicit egotism people should gravitate toward others who resemble them because similar others activate people's positive, automatic associations about themselves. Four archival studies and 3 experiments supported this hypothesis. Studies 1-4 showed that people are disproportionately likely to marry others whose first or last names resemble their own. Studies 5-7 provided experimental support for implicit egotism. Participants were more attracted than usual to people (a) whose arbitrary experimental code numbers resembled their own birthday numbers, (b) whose surnames shared letters with their own surnames, and (c) whose jersey number had been paired, subliminally, with their own names. Discussion focuses on implications for implicit egotism, similarity, and interpersonal attraction.     

Apparent Incentive Contrast Effects in Autoshaping with Rats

The effects of shifts in reward quality and quantity on Pavlovian acquisition were studied in rats. In Experiment 1, animals preexposed to unsignaled food pellets, 10% sucrose solution, or home cage controls subsequently received autoshaping training (response-independent lever-pellet or lever-solution pairings, in three groups each). Unsignaled preexposure to sucrose solution facilitated autoshaping for pellets (relative to unshifted controls), whereas unsignaled preexposure to pellets retarded autoshaping for sucrose solution. In Experiment 2, unsignaled preexposure to 30% sucrose solution impaired acquisition reinforced by food pellets, relative to 2% solution. Using a choice procedure, Experiment 3 demonstrated that rats prefer pellets to either 2 or 10% sucrose solutions, but they prefer the 30% solution to the pellets. Experiment 4 demonstrated the facilitatory effect after an upward shift in reward magnitude rather than quality (from 1 to 12 pellets), but provided weaker evidence for retardation following a downward magnitude shift. Experiment 5 was similar to Experiment 4, except that animals received autoshaping training from the outset. No evidence of successive positive contrast was obtained, but there was a significant successive negative contrast effect. Moreover, extinction was faster after acquisition with 12 pellets rather than 1. These results suggest the presence of incentive contrast effects under Pavlovian training conditions.     

Review essay

The Legacy of Erich Fromm by Daniel Burston. Cambridge, MA: Harvard University Press, 1991, xi + 260 pp., $29.95.     

Duration of extinction trials as a determinant of instrumental extinction in terrestrial toads (<Emphasis Type="Italic">Rhinella arenarum</Emphasis>)

Instrumental learning guides behavior toward resources. When such resources are no longer available, approach to previously reinforced locations is reduced, a process called extinction. The present experiments are concerned with factors affecting the extinction of acquired behaviors in toads. In previous experiments, total reward magnitude in acquisition and duration of extinction trials were confounded. The present experiments were designed to test the effects of these factors in factorial designs. Experiment 1 varied reward magnitude (900, 300, or 100 s of water access per trial) and amount of acquisition training (5 or 15 daily trials). With total amount of water access equated in acquisition, extinction with large rewards was faster (longer latencies in 900/5 than 300/15), but with total amount of training equated, extinction with small rewards was faster (longer latencies in 100/15 than 300/15). Experiment 2 varied reward magnitude (1200 or 120 s of water access per trial) while holding constant the number of acquisition trials (5 daily trials) and the duration of extinction trials (300 s). Extinction performance was lower with small, rather than large reward magnitude (longer latencies in 120/300 than in 1200/300). Thus, instrumental extinction depends upon the amount of time toads are exposed to the empty goal compartment during extinction trials.     

Fictions,Conditionals, and Stellar Astrophysics

This article argues in favour of an inferential role for fictions in scientific modelling. The argument proceeds by means of a detailed case study, namely models of the internal structure of stars in stellar astrophysics. The main assumptions in such models are described, and it is argued that they are best understood as useful fictions. The role that conditionals play in these models is explained, and it is argued that fictional assumptions play an important role as either background or antecedent conditions. I then expand on the argument for the compatibility of fictions and scientific realism. I argue that realism and antirealism plausibly offer correspondingly different accounts of the semantics of these fictional conditionals.     

The surprising potency of implicit egotism: A reply to Simonsohn

This article addresses Simonsohn's (2011) critique of field studies of implicit egotism. We argue that Simonsohn provides no compelling theoretical reason to believe that implicit egotism should be valid only in the laboratory. In addition, we argue that a careful analysis of most of Simonsohn's studies of implicit egotism shows that they provide little or no power to reveal real effects of implicit egotism. We conclude that it is more constructive to try to identify theoretically derived moderators of implicit egotism than to try to document that it is always spurious in the field.     

Pavlovian to instrumental transfer of control in a human learning task

Pavlovian learning tasks have been widely used as tools to understand basic cognitive and emotional processes in humans. The present studies investigated one particular task, Pavlovian-to-instrumental transfer (PIT), with human participants in an effort to examine potential cognitive and emotional effects of Pavlovian cues upon instrumentally trained performance. In two experiments, subjects first learned two separate instrumental response-outcome relationships (i.e., R1-O1 and R2-O2) and then were exposed to various stimulus-outcome relationships (i.e., S1-O1, S2-O2, S3-O3, and S4-) before the effects of the Pavlovian stimuli on instrumental responding were assessed during a non-reinforced test. In Experiment 1, instrumental responding was established using a positive-reinforcement procedure, whereas in Experiment 2, a quasi-avoidance learning task was used. In both cases, the Pavlovian stimuli exerted selective control over instrumental responding, whereby S1 and S2 selectively elevated the instrumental response with which it shared an outcome. In addition, in Experiment 2, S3 exerted a nonselective transfer of control effect, whereby both responses were elevated over baseline levels. These data identify two ways, one specific and one general, in which Pavlovian processes can exert control over instrumental responding in human learning paradigms, suggesting that this method may serve as a useful tool in the study of basic cognitive and emotional processes in human learning.     

On Quantum Propensities: Two Arguments Revisited

Peter Milne and Neal Grossman have argued against Popper's propensity interpretation of quantum mechanics, by appeal to the two-slit experiment and to the distinction between mixtures and superpositions, respectively. In this paper I show that a different propensity interpretation successfully meets their objections. According to this interpretation, the possession of a quantum propensity by a quantum system is independent of the experimental set-ups designed to test it, even though its manifestations are not.     

Scientific representation: against similarity and isomorphism

I argue against theories that attempt to reduce scientific representation to similarity or isomorphism. These reductive theories aim to radically naturalize the notion of representation, since they treat scientist's purposes and intentions as non-essential to representation. I distinguish between the means and the constituents of representation, and I argue that similarity and isomorphism are common but not universal means of representation. I then present four other arguments to show that similarity and isomorphism are not the constituents of scientific representation. I finish by looking at the prospects for weakened versions of these theories, and I argue that only those that abandon the aim to radically naturalize scientific representation are likely to be successful.