Deterministic Chaos and Computational Complexity: the Case of Methodological Complexity Reductions

Some problems rarely discussed in traditional philosophy of science are mentioned: The empirical sciences using mathematico-quantitative theoretical models are frequently confronted with several types of computational problems posing primarily methodological limitations on explanatory and prognostic matters. Such limitations may arise from the appearances of deterministic chaos and (too) high computational complexity in general. In many cases, however, scientists circumvent such limitations by utilizing reductional approximations or complexity reductions for intractable problem formulations, thus constructing new models which are computationally tractable. Such activities are compared with reduction types (more) established in philosophy of science. This revised version was published online in August 2006 with corrections to the Cover Date.     

Risk-Taking and Smoking Tendency Among Primarily African American School Children: Moderating Influences of Peer Susceptibility

We examined the hypothesis that peer susceptibility would moderate the association between risk-taking and tendency to smoke in adolescents who were primarily African American. Participants were 88 preadolescents recruited from a 6th grade classroom in a public elementary school. We found an interaction of risk-taking and susceptibility to peer influence on smoking tendency. Specifically, a moderator effect was found for peer influence on the association between risk-taking and smoking tendency. The importance of examining peer susceptibility on health promotion and other health behaviors in children and adolescents was supported.     

Eliminating automatic racial bias: Making race non-diagnostic for responses to criminal suspects

The current work proposes an approach for eliminating automatic bias by repeatedly exposing people to social stimuli where group membership (e.g., race) is unrelated to stereotypicality (e.g., being a violent criminal). Participants completed a computer program where they pretended they were police officers and decided as quickly as possible whether to shoot at Black and White suspects. Although initial responses to the program were biased by the race of the suspect, extensive practice with the program where race was unrelated to the presence or absence of a gun eliminated race biases immediately after practice (Study 1) and 24 h later (Study 2). However, this elimination of bias did not occur when race was related to the presence of a gun (Study 3). The final study (Study 4) revealed that extensive practice on the program led to the inhibition of racial concepts. The findings are discussed in terms of their implications for the elimination of automatic forms of bias.     

VOUCHER‐BASED CONTINGENT REINFORCEMENT OF SMOKING ABSTINENCE AMONG METHADONE‐MAINTAINED PATIENTS: A PILOT STUDY

This study evaluated the efficacy of a contingency management (CM) intervention to promote smoking cessation in methadone‐maintained patients. Twenty participants, randomized into contingent (n = 10) or noncontingent (n = 10) experimental conditions, completed the 14‐day study. Abstinence was determined using breath carbon monoxide and urine cotinine levels. Contingent participants received voucher‐based incentives for biochemical evidence of smoking abstinence. Noncontingent participants earned vouchers independent of smoking status. Contingent participants achieved significantly more smoking abstinence and longer durations of continuous smoking abstinence than did noncontingent participants. These results support the potential efficacy of using voucher‐based CM to promote smoking cessation among methadone‐maintained patients.     

Effects of Initial Abstinence and Programmed Lapses on The Relative Reinforcing Effects of Cigarette Smoking

Fifty-eight smokers received abstinence-contingent monetary payments for 1 (n  =  15) or 14 (n  =  43) days. Those who received contingent payments for 14 days also received 0, 1, or 8 experimenter-delivered cigarette puffs on 5 evenings. The relative reinforcing effects of smoking were assessed in a 3-hr session on the final study day, when participants made 20 choices between smoking or money. The reinforcement contingencies exerted robust control over smoking, and programmed smoking lapses produced few discernible effects. These results further illustrate the robust control that reinforcement contingencies can exert over cigarette smoking and suggest that any effects of lapses on the relative reinforcing effects of smoking are modest under conditions involving abstinence-contingent reinforcement contingencies.     

The Relative Contribution of Economic Valence to Contingency Management Efficacy: A Pilot Study

We investigated the extent to which a contingency management (CM) procedure that deducted money from a grand total available at the end of the study compared to a procedure in which money accumulated with continued abstinence from cigarette smoking. Results suggested that the procedure in which money increased contingent on abstinence resulted in a significantly greater likelihood of obtaining a clinically relevant (i.e., 48-hr) period of abstinence. In terms of attendance, participants in the condition in which monetary reinforcement accrued with consecutive instances of abstinence were significantly less likely to miss consecutive appointments than those in which money was deducted for failure to abstain.     

Stated reasons for reducing work-commute by car

A survey is reported that requested work-commuters by car to state reasons that would make them reduce car use for the work commute. All participants (n = 1218) were employed by companies located in the center of a medium-size Swedish city (pop. 82,000). Among 76% of the car users (n = 602) who stated any reasons, the most frequent were improved public transport and work from home some days. Shorter travel times, an increased frequency of service and lower fares were the most frequent reasons for increasing public transport use.     

The brain is both neurocomputer and quantum computer

In their article, Is the Brain a Quantum Computer,? Litt, Eliasmith, Kroon, Weinstein, and Thagard (2006) criticize the Penrose–Hameroff “Orch OR” quantum computational model of consciousness, arguing instead for neurocomputation as an explanation for mental phenomena. Here I clarify and defend Orch OR, show how Orch OR and neurocomputation are compatible, and question whether neurocomputation alone can physiologically account for coherent gamma synchrony EEG, a candidate for the neural correlate of consciousness. Orch OR is based on quantum computation in microtubules within dendrites in cortex and other regions linked by dendritic–dendritic gap junctions (“dendritic webs”) acting as laterally connected input layers of the brain's neurocomputational architecture. Within dendritic webs, consciousness is proposed to occur as gamma EEG‐synchronized sequences of discrete quantum computational events acting in integration phases of neurocomputational “integrate‐and‐fire” cycles. Orch OR is a viable approach toward understanding how the brain produces consciousness.     

Still No Evidence For Temporally Extended Shock-frequency Reduction As A Reinforcer.

There is no consensus and very little overlap in the criticisms of my target article. Because the primary consequences of avoidance behavior are by definition alterations in the distribution of shocks in time, any theory about the reinforcement of such behavior necessarily must begin with that dimension. However, the safety‐signal version of two‐process theory calls on positively and negatively correlated stimuli, including the responses themselves serving as stimuli, to transmit the effects of those alterations to the relevant behavior. Meanwhile, the Herrnstein—Hineline single‐process theory hypothesizes an additional source of reinforcement: a direct effect of reduction in the density of shock over some extended period of time. I can find no data that selectively support that hypothesis.     

The molarity of molecular theory and the molecularity of molar theory.

Dinsmoor (2001) rejects shock-frequency reduction as a reinforcer for avoidance behavior, and considers this to be an invalidation of so-called molar avoidance theory. This is a narrow view of operant avoidance theory, for which shock-frequency reduction is by no means the only reinforcer.