Discrimination of dynamic change and constancy over time by pigeons

The detection of change over time is critical to the serial integration of reality. Three pigeons, in a same/different go/no-go discrimination, were rewarded for pecking at changing stimuli that oscillated back and forth in brightness over a specific range and not at constant, unchanging stimuli randomly selected from the same range. Experiment 1 tested their capacity to detect increasingly slower rates of change against a constant control. The results indicated that pigeons retrospectively integrate past experience over approximately 20–30 s. Experiment 2 tested combinations of brightness ranges and rates to examine the possible roles of perception and memory in this discrimination. Overall, the results indicate that pigeons can detect continuous changes in brightness over different temporal durations, and several lines of evidence suggest that a combination of perception and memory mechanisms are involved. Implications for the pigeons’experience of the recent past are considered.     

Role of amygdala-prefrontal cortex circuitry in regulating the expression of contextual fear memory

The basolateral amygdala (BLA) and medial prefrontal cortex (mPFC) are inter-connected regions involved in fear memory expression. The reciprocal nature of projections between these areas differs along the rostrocaudal extent of BLA. This study investigated the role of functional interactions between BLA and the prelimbic (PL) subregion of mPFC in mediating contextual fear memory. Freezing served as the measure of conditioned fear. Experiments 1–3 examined the effects of left, right or bilateral infusion of bupivacaine into anterior BLA (aBLA), posterior BLA (pBLA) or PL on fear memory expression. Reversible inactivation of left, right or bilateral aBLA impaired fear memory expression. Bilateral inactivation of pBLA or PL also disrupted the expression of fear memory, although left or right inactivation alone had no significant effects in either region. Experiment 4 examined the effects of functionally disconnecting pBLA and PL on contextual fear memory by infusing bupivacaine unilaterally into pBLA and PL in the ipsilateral or contralateral hemisphere. Fear memory expression was impaired by asymmetric inactivation of pBLA and PL; however, a similar effect was also observed with symmetric inactivation of these regions. Bupivacaine infusion did not affect behavior in the open field, likely ruling out non-specific effects of inactivation on innate fear and locomotor activity. These results demonstrate different roles for rostral and caudal BLA in mediating the expression of contextual fear memory. They also raise the possibility that pBLA–PL circuitry is involved in subserving fear memory expression via complex processing mechanisms, although further research is needed to confirm this preliminary finding.     

An Absolutist Theory of Faultless Disagreement in Aesthetics

Some philosophers writing on the possibility of faultless disagreement have argued that the only way to account for the intuition that there could be disagreements which are faultless in every sense is to accept a relativistic semantics. In this article we demonstrate that this view is mistaken by constructing an absolutist semantics for a particular domain – aesthetic discourse – which allows for the possibility of genuinely faultless disagreements. We argue that this position (Humean absolutism) is an improvement over previous absolutist responses to the relativist's challenge and that it presents an independently plausible account of the semantics of aesthetic discourse.     

The detection and treatment of artifacts in computer-controlled neurophysiological experiments

Pattern recognition algorithms may be employed on time-series data obtained in electrophysiological experiments to detect particular artifacts that would otherwise contaminate the experimental data. Such algorithms may be classified by the statistical properties of the data they test. Four representative algorithms are presented that, on the basis of prior experiments in our laboratory, perform satisfactorily to improve the quality of electrophysiological measurement.     

Rate of response as a visual social stimulus

In Exp. 1, a high rate of responding (chain pulling) of a stimulus monkey was established as a visual positive discriminative stimulus for the operant behavior (bar pressing) of an observer monkey. The terminal performance of the observer under conditions in which a high rate of response of the stimulus monkey alternated in a variable temporal arrangement with a zero rate of response of the stimulus monkey (negative discriminative stimulus) was essentially the same as when nonbehavioral stimuli are correlated with the availability of reinforcement. By manipulating the schedule of reinforcement to change the rate of responding of the stimulus subject without changing its rate of reinforcement, Exp. 2 showed that the effective behavioral stimulus for the observer was the rate of chain pulling by the stimulus subject. A novel intermediate rate of responding by the stimulus monkey resulted in an intermediate rate (generalization) on the part of the observer during an extinction test. These experiments demonstrated that the rate of responding of one organism can function as a discriminative stimulus to control the rate of responding of another organism; and that the rate of responding is similar to other physical stimuli in terms of discrimination and generalization.     

Individual Differences in Risky Decision Making: A Meta‐analysis of Sensation Seeking and Impulsivity with the Balloon Analogue Risk Task

To represent the state‐of‐the‐art in an effort to understand the relation between personality and risk taking, we selected a popular decision task with characteristics that parallel risk taking in the real world and two personality traits commonly believed to influence risk taking. A meta‐analysis is presented based on 22 studies of the Balloon Analogue Risk Task from which correlations with sensation seeking and impulsivity assessments could be obtained. Results calculated on a total of 2120 participants showed that effect size for the relation of sensation seeking with risk taking was in the small–moderate range ( = .14), whereas the effect size for impulsivity was just around the small effect size threshold ( = .10). Although we considered participants' demographics as moderators, we found only significantly larger effect sizes for the older adolescents and young adults compared with other ages. The findings of the present review supported the view that inconsistencies in personality–risk research were mostly due to random fluctuations of specific effect sizes, rather than to lack of theoretical ties or to measurement unreliability. It is also concluded that studies aimed at relating individual differences in personality to performance in experimental decision tasks need an appropriate sample size to achieve the power to produce significant results. Copyright © 2013 John Wiley & Sons, Ltd.     

Intra-Individual Variability of Normal and Educable Mentally Retarded Children on a Coincidence Timing Task

A visual coincidence timing task was used to compare the level of performance (constant error) and the intra-individual variability of 100 normal and 100 educable mentally retarded children. The mean performance of the intellectually normal children on this task was significantly superior to that of the retarded children, and the intra-individual variability of the latter was significantly greater than that of the former. The hypothesis that high intra-individual variability and depressed level of performance are closely associated was not supported.