Luke P. Simmons

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Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the(More)
Killeen and Fetterman's (1988) behavioral theory of animal timing predicts that decreases in the rate of reinforcement should produce decreases in the sensitivity (A') of temporal discriminations and a decrease in miss and correct rejection rates (decrease in bias toward "long" responses). Eight rats were trained on a 10- versus 0.1-s temporal(More)
Rats were injected with saline, 1.0 mg/kg or 2.6 mg/kg of diisopropyl phosphorofluoridate (DFP). Three days later the animals were placed in cages in which they could press a lever to obtain their entire daily ration of food. The time of day at which responses occurred and the time between successive responses were recorded over a six day period to(More)
The hypothesis that time perception is determined by an internal clock's rate, which is sensitive to physiological circadian changes was examined. This hypothesis suggests that when body temperature and activity increase, clock rate increases causing overestimations of time and a decrease in time interval production. The following experiments examine this(More)
Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) are pressing medical issues for the Warfighter. Symptoms of mTBI can overlap with those of PTSD, suggesting the possibility of a causal or mediating role of mTBI in PTSD. To address whether mTBI can exacerbate the neurobiological processes associated with traumatic stress, we(More)
The effects of cholinergic drugs on three different perceptual bisection tasks were studied in rats. Physostigmine (0.056-0.56 mg/kg), a reversible anticholinesterase, produced dose-dependent decrements in discriminability (A'), but did not affect the bisection point (BP) in visual duration, auditory duration, and auditory intensity bisection tasks. This(More)
Three experiments were conducted to study the effect of an imperfect substitute for food on demand for food in a closed economy. In Experiments 1 and 2, rats pressed a lever for their entire daily food ration, and a fixed ratio of presses was required for each food pellet. In both experiments, the fixed ratio was held constant during a daily session but was(More)
The hypothesis that DFP alters circadian rhythms by altering the output of an "internal clock" which is also used to time events in behavioral tasks was tested. Since any clock has a mean rate (ticks/unit time) and an associated variance (changes in the rate across time), measures of time perception which depend upon both the mean clock rate and its(More)
The bisection method of animal psychophysical scaling was examined as a measurement procedure. The critical assumptions of bisection scaling, as described by Pfanzagl (1968), were tested to determine if a valid equal-interval scale could be derived. A valid scale was derived in which loudness for the rat (Rattus norvegicus; n = 13) was a power function of(More)
In this paper we discuss the development of a low cost surface electromyography (sEMG) system and its efficacy as a mechanism for human-machine interfaces. By reducing the size of the surface electromyography hardware to a compact form makes its use as a wearable interface feasible. Reducing both the system cost and complexity while maintaining signal(More)