Once is too much: Conditioned changes in accumbens dopamine following a single saccharin-morphine pairing.

The present study tested whether presentation of a taste cue would support conditioned suppression of dopamine in the nucleus accumbens (NAcc) following a single taste-drug pairing. Nondeprived male Sprague-Dawley rats were given 20-min access to a 0.15% saccharin conditioned stimulus (CS). Immediately thereafter, experimental rats were injected with morphine (15 mg/kg ip); standard controls were injected with saline; and explicitly unpaired controls were injected with morphine, but approximately 24 hr later. All rats were then given one 20-min CS-only test. Microdialysis samples from the NAcc were measured over 20-min intervals before, during, and after CS access on the conditioning and test trial. The results showed that a single saccharin-morphine pairing led to a marked reduction in CS intake, and the reduction in intake was accompanied by a conditioned blunting of the accumbens dopamine response to the saccharin reward cue. In turn, a single exposure to the saccharin cue also blunted the unconditioned dopamine response to morphine. Reward comparison effects, then, are cross-modal, bidirectional, and immediate, resulting in both unconditioned and conditioned changes in brain and behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

“Causal reasoning” in rats: A reappraisal.

It has recently been argued that rats engage in causal reasoning and they do so in a way that is consistent with Bayes net theories (Blaisdell, Sawa, Leising & Waldmann, 2006). This argument was based upon the finding that the tendency of cues to elicit approach to a food-well was reduced when their presentation was contingent on lever pressing. There is, however, an alternative interpretation of the critical experimental findings that is based on the simple principle of response competition: wherein lever pressing interferes with the tendency to approach the food well. Here the authors replicated Experiments 1 and 2a of Blaisdell et al. (2006) and found reciprocal patterns of lever pressing and food well approach during the critical cues. These results lend direct support for an interpretation in terms of response competition while providing evidence contrary to Bayes net theories, and are readily interpreted within the theoretical framework provided by traditional associative learning theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On reasoning from predicates: The PhD is not a professional degree.

Counters E. J. Shoben's (see record 1981-26598-001) arguments in favor of retaining the PhD degree as the most appropriate credential for professional practice. It is argued that (1) the ability to think critically and to write in a scholarly manner can be demonstrated by other means than the writing of a dissertation and the awarding of a PhD (accreditation standards and licensing regulations require a doctorate not a PhD); (2) although most faculty in professional schools and practitioners have a PhD, this reflects the fact that until recently no PsyD degrees were awarded; (3) psychology is solidly established enough as a profession to win acceptance of a separate professional degree; and (4) methods are proposed for preventing the PsyD from being perceived, incorrectly, as a watered down degree. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal reasoning in the social and nonsocial realms.

Examines the literature on the development of causal reasoning about social and physical phenomena. Contrary to previous claims, causal reasoning is neither identical nor substantially different across these 2 realms. Instead, there is fundamental overlap that derives from the fact that both social and physical causation are interpreted in generative, rather than empiricist, terms. Differences stem from the fact that the mechanism of causal generation differs in the 2 arenas. Physical effects are generated by transmissions of energy, whereas social or behavioral effects are generated by the enactment of intentions. Some causal inference rules are restricted to one domain or the other, while other rules are common to both domains. Young children were found not to confuse social and physical causation as previously claimed. (French abstract) (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal relations and feature similarity in children's inductive reasoning.

Four experiments examined the development of property induction on the basis of causal relations. In the first 2 studies, 5-year-olds, 8-year-olds, and adults were presented with triads in which a target instance was equally similar to 2 inductive bases but shared a causal antecedent feature with 1 of them. All 3 age groups used causal relations as a basis for property induction, although the proportion of causal inferences increased with age. Subsequent experiments pitted causal relations against featural similarity in induction. It was found that adults and 8-year-olds, but not 5-year-olds, preferred shared causal relations over strong featural similarity as a basis for induction. The implications for models of inductive reasoning and development are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal reasoning in the attribution of rare and common events.

Three studies investigated causal reasoning when 2 dispositions—one more common than the other—are both consistently associated with a behavior. Ss rated the rare disposition as the more important cause when the behavior itself was rare but violated the covariation principle by rating the common disposition as more important when the behavior was relatively common. Results suggest that use of the covariation principle may be the most important heuristic for inferring causality only when the action to be explained is relatively rare. When the behavior is a common one, causal attributions may be more influenced by a principle of generative strength, with observers assigning greater causal importance to the disposition they believe to be stronger. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bewail the Vail: or Love is not enough.

Comments on 2 disappointing aspects of a conference on the training of psychologists. These aspects were the lack of attention to psychology as a basic science of behavior, and the definition of a psychologist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reinforcement is not enough: Learned expectancies and infant behavior.

Comments that J. L. Gewirtz and M. Peláez-Nogueras (see record 1993-12989-001) should be congratulated for reminding infant researchers of the methodological and conceptual debt owed to B. F. Skinner and for highlighting the contributions that behavior analysis offers for an understanding of infant behavior and development. It is contended that the concept of reinforcement, although a powerful process in infant behavior and development, is incapable of explaining many of the findings of infant researchers, including those who rely on operant conditioning as their paradigm of choice. The concept of expectancy is suggested as an adjunct to reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Competition between multiple causes of a single outcome in causal reasoning.

[Correction Notice: An erratum for this article was reported in Vol 35(2) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2009-05154-015). The URL provided for the supplemental material was incomplete. The complete URL is http://dx.doi.org/10.1037/a0012699.supp] A strong positive predictor of an outcome modulates the causal judgments of a moderate predictor. To study the empirical basis of this modulation, we compared treatments with one and with two strong competing (i.e., modulating) causes. This allowed us to vary the frequency of outcome occurrences or effects paired with the predictors. We investigated causal competition between positive predictors (those signaling the occurrence of the outcome), between negative predictors (those signaling the absence of the outcome) and between predictors of opposite polarity (positive and negative). The results are consistent with a contrast rather than a reduced associative strength or conditional contingency account, because a strong predictor of opposite polarity enhances rather than reduces causal estimates of moderate predictors. In addition, we found competition effects when the strong predictor predicted fewer outcome occurrences than the moderate predictor, thus implying that cue competition is, at least sometimes, a consequence of contingency rather than total cue-outcome pairings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition memory and attentional selection: Serial scanning is not enough.

In 2 experiments with a total of 54 graduate or undergraduate students, using memory sets of up to 10 letters, the response competition paradigm was employed to investigate the extent to which extraneous visual stimuli interfere with or affect the process of memory search. It was assumed that if selective attention could exclude the effect of noise letters from a Sternberg-type (S. Sternberg; see record 1966-10810-001) memory comparison process, then there would be an increase in intercept for the reaction time (RT)–set size functions but no increase in slope. This result was obtained. However, a large difference in response times to both positive and negative set targets were found when the accompanying noise letters indicated a competing response, as opposed to when they indicated the same response as the target. It is suggested that this implies rapid identification of the nature of both target and noise, independent of a serial comparison process. A modification of a dual process model (J. F. Juola et al; see record 1972-00186-001) in which stimuli activate a familiarity value independent of memory search was suggested to account for these results. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting reasoning from memory.

In an effort to assess the relations between reasoning and memory, in 8 experiments, the authors examined how well responses on an inductive reasoning task are predicted from responses on a recognition memory task for the same picture stimuli. Across several experimental manipulations, such as varying study time, presentation frequency, and the presence of stimuli from other categories, there was a high correlation between reasoning and memory responses (average r = .87), and these manipulations showed similar effects on the 2 tasks. The results point to common mechanisms underlying inductive reasoning and recognition memory abilities. A mathematical model, GEN-EX (generalization from examples), derived from exemplar models of categorization, is presented, which predicts both reasoning and memory responses from pairwise similarities among the stimuli, allowing for additional influences of subtyping and deterministic responding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Successful outcome and number of sessions: When do counselors think enough is enough?

60 counselors rated 166 female and 97 male clients seen at a university counseling center over a 3-yr period on 4 outcome measures: psychic distress, interpersonal relations, performance, and overall severity of client's problem. Improvement was studied as a function of the number of weekly sessions for which clients were seen. Results reveal that through 20 sessions there was a strong and consistent (across all outcome measures) positive linear relationship between treatment length and counselor-assessed outcome. After 20 sessions, however, additional counseling was no longer associated with further increases in the rate of improvement. The "failure zone" reported in some earlier studies was not observed. The implications of these findings for clinical practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What is missing in Chinese-Western dialectical reasoning.

Comments on the article by K. Peng and R. E. Nisbett (see record 1999-11125-001) that made a number of assertions that reveal problems in logic and argumentation. In their studies, Peng and Nisbett found that Chinese tended to like dialectical proverbs and social resolution better than did Americans, and Chinese tended to prefer dialectical arguments over classic Western logical arguments. In the present article, the author argues that cultural, ecological, and historical factors may account for the difference between Chinese and European Americans in their thinking; however, the question of whether Chinese tend to be essentially different from Westerners in their cognitive reasoning remains controversial and awaits more research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Needle exchange is not enough: lessons from the Vancouver injecting drug use study

OBJECTIVE: To describe prevalence and incidence of HIV-1, hepatitis C virus (HCV) and risk behaviours in a prospective cohort of injecting drugs users (IDU). SETTING: Vancouver, which introduced a needle exchange programme (NEP) in 1988, and currently exchanges over 2 million needles per year. DESIGN: IDU who had injected illicit drugs within the previous month were recruited through street outreach. At baseline and semi-annually, subjects underwent serology for HIV-1 and HCV, and questionnaires on demographics, behaviours and NEP attendance were completed. Logistic regression analysis was used to identify determinants of HIV prevalence. RESULTS: Of 1006 IDU, 65% were men, and either white (65%) or Native (27%). Prevalence rates of HIV-1 and HCV were 23 and 88%, respectively. The majority (92%) had attended Vancouver's NEP, which was the most important syringe source for 78%. Identical proportions of known HIV-positive and HIV-negative IDU reported lending used syringes (40%). Of HIV-negative IDU, 39% borrowed used needles within the previous 6 months. Relative to HIV-negative IDU, HIV-positive IDU were more likely to frequently inject cocaine (72 versus 62%; P < 0.001). Independent predictors of HIV-positive serostatus were low education, unstable housing, commercial sex, borrowing needles, being an established IDU, injecting with others, and frequent NEP attendance. Based on 24 seroconversions among 257 follow-up visits, estimated HIV incidence was 18.6 per 100 person-years (95% confidence interval, 11.1-26.0). CONCLUSIONS: Despite having the largest NEP in North America, Vancouver has been experiencing an ongoing HIV epidemic. Whereas NEP are crucial for sterile syringe provision, they should be considered one component of a comprehensive programme including counselling, support and education.     

CHARM is not enough: Comments on Eich's model of cued recall.

Comments on the claim of J. M. Eich (see record 1983-04922-001) that the proposed composite holographic associative recall model (CHARM) provides a good account of the empirical findings by the present authors (see record 1973-20189-001) that are associated with the levels-of-processing approach to the study of memory. It is asserted that although CHARM simulates the results of several relevant studies, it does so by making assumptions different from those embodied in levels of processing. In particular, Eich's central assumption that well-remembered events are characterized by high levels of similarity between the target item and its context is questioned. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal drift is enough to drive a single microtubule along its axis even in the absence of motor proteins

One-dimensional diffusion of microtubules (MTs), a back-and-forth motion of MTs due to thermal diffusion, was reported in dynein motility assay. The interaction between MTs and dynein that allows such motion was implicated in its importance in the force generating cycle of dynein ATPase cycle. However, it was not known whether the phenomenon is special to motor proteins. Here we show two independent examples of one-dimensional diffusion of MTs in the absence of motor proteins. Dynamin, a MT-activated GTPase, causes a nucleotide dependent back-and-forth movement of single MT up to 1 micron along the longitudinal axes, although the MT never showed unidirectional consistent movement. Quantitative analysis of the motion and its nucleotide condition indicates that the motion is due to a thermal driven diffusion, restricted to one dimension, under the weak interaction between MT and dynamin. However, specific protein-protein interaction is not essential for the motion, because similar back-and-forth movement of MT was achieved on coverslips coated with only 0.8% methylcellulose. Both cases demonstrate that thermal diffusion could provide a considerable sliding of MTs only if MTs are restricted on the surface appropriately.