A procedure for studying strategy development in humans

An early version of the computer gameStar Trek was modified to conduct behavioral research. By appropriate use of the starship’s weapon and defense systems, the player can kill enemy ships and avoid destruction. The player’s moves, as well as the time and state of the game environment when each move occurs, are recorded. The procedure tracks performance changes over time very well, and allows the dissection of performance into sequences of commands that reflect the subject’s play strategy. Computer games such asStar Trek could be the basis for experiments that bridge the gap between operant and cognitive research.     

A Note on Finiteness in the Predicative Foundations of Arithmetic

Recently, Feferman and Hellman (and Aczel) showed how to establish the existence and categoricity of a natural number system by predicative means given the primitive notion of a finite set of individuals and given also a suitable pairing function operating on individuals. This short paper shows that this existence and categoricity result does not rely (even indirectly) on finite-set induction, thereby sustaining Feferman and Hellman's point in favor of the view that natural number induction can be derived from a very weak fragment of finite-set theory, so weak that finite-set induction is not assumed. Many basic features of finiteness fail to hold in these weak fragments, conspicuously the principle that finite sets are in one-one correspondence with a proper initial segments of a (any) natural number structure. In the last part of the paper, we propose two prima facie evident principles for finite sets that, when added to these fragments, entail this principle.     

Neural Processing to Visual Stimuli in a Three-Choice Reaction-Time Task

Some authors have suggested that certain components of the event-related potentials (ERPs) reflect underlying stages in the discrimination process. Previous studies have shown that in an auditive three-choice reaction-time task the discrimination is accomplished as a two-stage process, with the more frequently occurring stimulus discriminated at an earlier point than the rarer stimulus and the subjects could be classified as fast and slow responders in function of their response to the most frequent of the three tones. We continuously recorded the electrocerebral activity (EEG) from the scalp and the electromyographic activity (EMG) from the responding muscles in a visual three-choice reaction-time task in 10 strictly right-handed subjects. EEG and EMG responses were subsequently analyzed off-line by aligning them by the onset of either the stimulus (stimulus-synchronized) or the response (response-synchronized). The results suggest that processes of visual stimuli evaluation and response execution are continuously integrated. The discrimination and response systems to visual stimuli is accomplished as a three-stage process, one to frequent tone, another for rare 1, and the last for rare 2. The subjects were classified as fast and slow responders in function of their response to the most frequent of the three tones.     

Hoops and Barns: a new dilemma for Sosa

Synthese - This paper critically assesses Sosa’s normative framework for performances as well as its application to epistemology. We first develop a problem for one of Sosa’s central...     

The paraventricular nucleus of the hypothalamus is involved in cardiovascular responses to acute restraint stress in rats

The paraventricular nucleus of the hypothalamus (PVN) has been implicated in several aspects of cardiovascular control. Stimulation of the PVN evokes changes in blood pressure and heart rate. Additionally, this brain area is connected to several limbic structures implicated in behavioral control, as well as to forebrain and brainstem structures involved in cardiovascular control. This evidence indicates that the PVN may modulate cardiovascular correlates of behavioral responses to stressful stimuli. Acute restraint is an unavoidable stressor that evokes marked and sustained cardiovascular changes, which are characterized by elevated mean arterial pressure (MAP) and an intense heart rate (HR) increase. We report on the effect of inhibition of PVN synapses on MAP and HR responses evoked by acute restraint in rats. Bilateral microinjection of the nonspecific synaptic blocker cobalt (CoCl(2), 1 mM/100 nl) into the PVN did not change the HR response or the initial peak of the MAP response to restraint stress, but reduced the area under the curve of the MAP response. Moreover, bilateral microinjection of cobalt in areas surrounding the PVN did not change the cardiovascular response to restraint. These results indicate that synapses in the PVN are involved in the neural pathway that controls blood pressure changes evoked by restraint.