Some discriminative properties of fixed ratio performance in the pigeon

The discriminative control over a spatial choice response exercised by prior behavior was studied using a procedure involving discrete exposures to a two-member chained schedule. The initial member (red key) was either a smaller or larger fixed ratio (Mix FR:FR), the completion of which produced, after a 1-sec delay, two white response keys. If the larger FR had been completed as the initial chain member, a single peck on the right white key was reinforced; after the smaller FR, a peck on the left white key was reinforced. Frequencies of unreinforced responses (S(Delta) responses) were determined with several pairs of red-key FRs: 95-5, 75-25, 65-35, 60-40, 58-42 and 50-50. The S(Delta) response frequencies were low through the FR pair 65-35; sharp increases were obtained with pairs 60-40 and 58-42. Later, curves analogous to stimulus generalization functions were obtained using a probe procedure. Finally, the delay interval between completion of a red-key FR and the white-key choice response was manipulated: results were variable, but S(Delta) response frequencies tended to increase with increasing delays.     

The Systematicity of Davidson’s Anti-skeptical Arguments

Topoi - Donald Davidson contributed more deeply to our understanding of language, thought, and reality than perhaps any other recent philosopher. His discussions of skepticism are sometimes seen as...     

Program for advanced studies in integrative psychotherapy: Family,couple, and individual therapy (an interdisciplinary program)

This article describes briefly an advanced program in integrative marital and family therapy and individual psychotherapy established at the Hebrew University of Jersusalem in 1993–94 and its first two years of successful operation.     

A system for controlling the light output of a monochromator by any simple function and for temporally modulating the intensity

This paper describes an apparatus that controls the output of a monochromator so that the energies in each waveband can be equated according to any desired function. A photocell monitors the light from the monochromator and provides a feedback to the power supply driving the lamp. A function generatoris mechanically linked to the monochromator’s wavelength drive and provides the function for correcting the output spectrum. Once set, the light output remains constant even if the bulb ages or is replaced. If desired, a sinusoidalripple of variable frequency and amplitude can be imposed on the mean intensity of the light.     

Cultural phenomena and the research enterprise: Toward a culturally anchored methodology

Highlights the points at which culture intersects major phases of the research enterprise — problem formulation, population definition, concept and measurement development, research design, methodology, and data analysis — and influences and constrains what researchers deem worthy of investigation and how they interpret what they observe. These ethnocentric biases inhibit the development of a knowledge base for understanding diverse cultural communities. At each step of the research process, the need to carefully examine and expose the underlying cultural assumptions and to generate and develop alternative choices is emphasized. Guidelines are provided to encourage researchers to be aware of and deliberately make choices toward the development of a culturally anchored methodology that balances the demands for rigor and sensitivity.     

Single prolonged stress disrupts retention of extinguished fear in rats

Clinical research has linked post-traumatic stress disorder (PTSD) with deficits in fear extinction. However, it is not clear whether these deficits result from stress-related changes in the acquisition or retention of extinction or in the regulation of extinction memories by context, for example. In this study, we used the single prolonged stress (SPS) animal model of PTSD and fear conditioning procedures to examine the effects of prior traumatic stress on the acquisition, retention, and context-specificity of extinction. SPS administered one week prior to fear conditioning had no effect on the acquisition of fear conditioning or extinction but disrupted the retention of extinction memories for both contextual and cued fear. This SPS effect required a post-stress incubation period to manifest. The results demonstrate that SPS disrupts extinction retention, leading to enhanced fear renewal; further research is needed to identify the neurobiological processes through which SPS induces these effects.     

Unconditioned freezing is enhanced in an appetitive context: implications for the contextual dependency of unconditioned fear

It has been well established that expression of conditioned fear is context independent, but the context dependency of unconditioned fear expression has rarely been explored. A recent study reported that unconditioned freezing in rats is enhanced in a familiar context, which suggests that unconditioned fear expression can be modulated by contextual processing. In order to further explore this possibility we examined unconditioned freezing in novel, familiar, and appetitive contexts; and attempted to identify brain regions critical for context-related changes in unconditioned freezing by measuring c-Fos mRNA levels in emotional circuits. Unconditioned freezing was enhanced in the appetitive context, and this enhancement was accompanied by increased c-Fos mRNA expression in the medial amygdala and hippocampus, but attenuated expression in the medial prefrontal cortex. In the appetitive context, expectation of a reward coupled with detection of threat may have enhanced unconditioned fear expression, which suggests that unconditioned fear expression can be modulated by contextual factors. Context-related expectancy mismatch may explain the enhancement of unconditioned fear expression seen in this study and warrants further examination.