Interval timing under a behavioral microscope: Dissociating motivational and timing processes in fixed-interval performance

The distribution of latencies and interresponse times (IRTs) of rats was compared between two fixed-interval (FI) schedules of food reinforcement (FI 30 s and FI 90 s), and between two levels of food deprivation. Computational modeling revealed that latencies and IRTs were well described by mixture probability distributions embodying two-state Markov chains. Analysis of these models revealed that only a subset of latencies is sensitive to the periodicity of reinforcement, and prefeeding only reduces the size of this subset. The distribution of IRTs suggests that behavior in FI schedules is organized in bouts that lengthen and ramp up in frequency with proximity to reinforcement. Prefeeding slowed down the lengthening of bouts and increased the time between bouts. When concatenated, latency and IRT models adequately reproduced sigmoidal FI response functions. These findings suggest that behavior in FI schedules fluctuates in and out of schedule control; an account of such fluctuation suggests that timing and motivation are dissociable components of FI performance. These mixture-distribution models also provide novel insights on the motivational, associative, and timing processes expressed in FI performance. These processes may be obscured, however, when performance in timing tasks is analyzed in terms of mean response rates.     

The ‘Nature of Science’ and the Perils of Epistemic Relativism

Research in Science Education - There is an increasing demand in the field of science education for the incorporation of philosophical and sociological aspects that are related to the scientific...     

Reading Aloud Narrative Material as a Means for the Student's Cognitive Empowerment

Listening to stories and brain processing of narrative material activates many areas devoted not only to the linguistic processing. In this sense, it could be hypothesized that if this activity would be integrated within the school curricula, it could bring benefits in terms of understanding the text as well as in basic essential cognitive dimensions. In a series of studies with different age groups, we investigated the effects of an intensive training in narrative listening, through different tools such as the standardized tests of understanding of the text. We also used a neuropsychological battery investigating basic cognitive processes (cognitive assessment system) that are directly related to the ability of text comprehension. Results show a significant improvement in all tests for all age groups in the experimental groups, in comparison with the control groups.     

Social constructs regarding the physical and sexual energy of whites,indigenous South Americans and blacks in Spanish and Colombian primary school reading books between 1900 and 1960*

This article analyses the manner in which the physical and sexual energy of the white, native South American and black populations was represented in reading books for elementary school children in Spain and Colombia between 1900 and 1960. Ninety reading books from representative authors were examined. It was found that the ideal of extraordinary physical vigour attributed to the white male was decisive in justifying Spanish imperialism, the superiority of the male in the patriarchal family and the intervention of authorities in administering people’s bodies. In the case of Spanish texts, the might attributed to the white race was shown as having a motive of pride, whereas in the Colombian case, the mixture with Native Americans and blacks tended to be used as an explanation for the ‘weakness’ of Colombians. Evidence is also found of the way in which education was implicitly conceived as a process of cultural ‘whitening’.     

Double poling kinematic changes during the course of a long-distance race: effect of performance level

ABSTRACT

We aimed to evaluate the changes in double poling (DP) kinematics due to a long-distance cross-country skiing race in athletes with different performance levels. A total of 100 cross-country skiers, belonging to 10 different performance groups, were filmed on flat terrain 7 and 55 km after the start line, during a 58-km classical race. Cycle velocity, frequency and length decreased from the best to the lower-ranked group, while duty cycle increased (all P <.001). Between track sections, cycle velocity and length decreased, duty cycles increased (all P <.001) while frequency was unaltered (P =.782). Group*section interactions resulted for cycle velocity (P =.005). Considering all the participants together, % change in cycle velocity between sections correlated with % change in length and duty cycle (all P <.001). Thus i) skiers in better groups showed longer and more frequent cycles as well as shorter duty cycles than skiers in slower groups; ii) throughout the race all the groups maintained the same cycle frequency while decreasing cycle velocity and length; iii) better groups showed a lower reduction in cycle velocity. Individually, a low reduction in cycle velocity during the race related to the capacity to maintain long cycles and short duty cycles.     

Early social communication development in infants with autism spectrum disorder

Social-communication differences are a robust and defining feature of autism spectrum disorder (ASD) but identifying early points of divergence in infancy has been a challenge. The current study examines social communication in 9- to 12-month-old infants who develop ASD (N = 30; 23% female; 70% white) compared to typically developing (TD) infants (N = 94, 38% female; 88% white). Results demonstrate that infants later diagnosed with ASD were already exhibiting fewer social-communication skills using eye gaze, facial expression, gestures, and sounds at 9 months (effect size: 0.42–0.89). Moreover, three unique patterns of change across distinct social-communication skills were observed within the ASD group. This study documents that observable social-communication differences for infants with ASD are unfolding by 9 months, pointing to a critical window for targeted intervention.     

Learning by pigeons playing against tit-for-tat in an operant prisoner’s dilemma

Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner’s dilemma (IPD) matrix in which the “other player” (a computer) playedtit-for-tat. One key served as thecooperation(C) key; the other served as thedefection(D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and thefollowing peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked,cooperation (relative rate of C-pecks)—hence, self-control—increased for all the pigeons.     

The irony of rigor: ‘no-excuses’ charter schools at the intersections of race and disability

Across the United States, the ‘no-excuses’ charter school movement featuring strict discipline policies and rigorous academic standards has gained popularity among schools serving poor and working-class students of color. In this article, we examine how Black and Latinx parents of students with disabilities¹ negotiated and experienced these charter school practices of rigor, which disciplined, managed, and regulated students’ social differences. Drawing from a yearlong qualitative research study, we examine interviews with Black and Latinx parents who experienced conflict with charter schools and the school lawyers, along with school artifacts we gathered such as parent handbooks and website information. We found parents experienced what we refer to as the ‘irony of rigor:’ the contradictory double-movement through which students of color with disabilities desired inclusion into ‘rigorous’ charter schools which then excluded them using ‘rigor’ as a central feature of student pushout practices. We present the irony of rigor in three interrelated acts: Act I: the lure of rigor (i.e. what drew parents to charter schools); Act II: the body meets rigor (i.e. how schools disciplined and managed student differences); and Act III: the consequences of rigor (i.e., what happened to students and parents while and after experiencing rigorous practices). We contextualize the irony of rigor within the relationship between disability, race, and neoliberalism.     

The market for paintings in the Venetian Republic from Renaissance to Rococò

We study the art market in the Venetian Republic from 1550 to 1750 analyzing the determinants of the prices (adjusted for the cost of living measured by the price of wheat) of figurative paintings. Reputation of the painters, size of the paintings and other quantifiable factors affect prices as expected. Other relevant factors include the placement of the paintings (on altars, ceilings or walls), whose impact reflects differences in demand elasticities. We find evidence of the law of one price confirming price equalization between high and low demand geographical destinations and between different subjects. Finally, in a Schumpeterian perspective, we relate the temporal trend of the price of a representative painting with waves of artistic innovations, whose peacks were in the 1500s and in the 1700s with a dark Baroque age in the intermediate century.