Thomas Raslear

Rapid demand curves for behavioral economics

A method for determining the relationship between food consumption and the price of food (demand function) in behavioral economic experiments is described. Although previous methods have generally required as long as 40 days, the present method can generate a complete demand function within 7 days, and therefore may be more suitable for use in the evaluation of drugs, toxins, and physiological/anatomical interventions. Moreover, measures of circadian rhythmicity, post-reinforcement pause durations, and interresponse times can also be generated. Three experiments tested the stability of the method in a variety of procedural manipulations: repeated exposure to the procedure, increasing versus random daily food price, and size of daily changes in food price. The procedure generated demand functions that were similar to those that require more extended testing, and the demand functions were not generally affected by procedural manipulations. Body weight, which can also affect consumption, generally decreases with increases in the price of food; so this variable should be recorded and used as a covariate in analyzing demand functions. With the exception of circadian rhythmicity, the other measures were stable across procedural variations and showed expected changes as a function of food price: postreinforcement pause durations increased as price increased, but interresponse times did not.

The Quantitative Analysis of Economic Behavior With Laboratory Animals

Studies of animal behavior in the laboratory provide an extensive data set on economic behavior under controlled and replicable conditions. In the studies reported, the food consumption of rodents and non-human primates was studied under a wide variety of conditions of work effort, commodity value, and substitute availability. The results conformed to a single underlying demand function that assumed that demand elasticity was linear in price. Price was defined as a cost-benefit ratio that included consideration of both the effort of the work and the value of the commodity purchased. The parameters of the elasticity equation appeared related to the amount and temporal proximity of a substitute food.

Perceptual bias and response bias in temporal bisection

In a temporal bisection task with rats, perceptual bias and response bias were simultaneously varied through manipulations of stimulus spacing and the relative probability of reinforcement for correct responses. Both manipulations produced systematic changes in the bisection point. However, only manipulations of relative reinforcement probability produced significant variations in B″, a nonparametric index of response bias. This finding shows that the bisection point may be shifted by either a perceptual bias or a response bias. However, in the absence of an index of response bias, such as B″, shifts caused by perceptual effects are indistinguishable from those caused by response preferences.

Modification of acoustic and tactile startle by single microwave pulses

Single microwave pulses at 1.25 GHz were delivered to the head and neck of male Long-Evans rats as a prestimulus to acoustic and tactile startle. For acoustic startle, pulses averaging 0.96 microsecond in duration were tested with two specific absorption rate (specific absorption) ranges, 15.0-30.0 kW/kg (16.0-44.2 mJ/kg) and 35.5-86.0 kW/kg (66.6-141.8 mJ/kg), delivered 201, 101, 51, 3, and 1 ms before and 1 ms after onset of a startling noise. The low-intensity pulse did not affect peak amplitude, integral, or latency of the whole-body startle response. The high-intensity pulse at 101 and 51 ms inhibited the startle response by decreasing peak amplitude and integral; at 201 and 51 ms latency was increased. The high-intensity pulse at 1 ms enhanced the startle response by increasing peak amplitude and at 3 ms by increasing integral. For tactile startle, either microwave pulses averaging 7.82 microseconds in duration and 55.9-113.3 kW/kg (525.0-1055.7 mJ/kg) or 94 dB SPL clicks were delivered 157, 107, 57, and 7 ms before and 43 ms after onset of a startling air burst. The microwave pulse at 57 ms inhibited the startle response by decreasing peak amplitude; at 157, 107, 57, and 7 ms it increased latency. The microwave pulse at 43 ms after onset enhanced the startle response by increasing peak amplitude. The acoustic click at 157 and 57 ms inhibited the startle response by decreasing peak amplitude; at 157,2 107, and 57 ms it increased latency.(ABSTRACT TRUNCATED AT 250 WORDS)

Loudness bisection and masking in the rat (Rattus norvegicus)

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 sound pressure for 4-kHz tones. Masking noise reduced the discriminability of tonal stimuli but did not affect the bisection point. This result is consistent with an interval scale representation of loudness and demonstrates scale meaningfulness. Loudness bisection data that have been reported in the literature for 3 species (humans, rats, and pigeons) are in substantial agreement with our results.

CW microwave fields evoke body movements in bilaterally cochleotomized rats

The probability of a whole-body movement in rats exposed to one second microwave pulses is a function of power. This functional relationship is similar in deafened and hearing rats, which eliminates microwave hearing as a possible mechanism for the effect. Observed thermal gradients in the facial skin support the hypothesis that tactile sensations are the eliciting stimulus for the whole-body movement, but do not address the hypothesis that microwave fields exert a direct effect on the central nervous system to cause the movement.

A Surgical Technique for Bilateral Cochleotomy in the Long-Evans Rat

A bilateral cochleotomized surgical rat model, needed for a study involving microwave effects, was developed, standardized, and assessed for reproducibility. After a review of the literature concerning attempts and approaches with various species, a technique involving an approach through the external auditory canal was chosen and modified. Using a stereomicroscope, a cutaneous incision in the intertragic notch was made and extended medially along the ventral aspect of the external auditory canal to the depth of the external auditory meatus. The tympanic membrane was ruptured and the malleus removed with splinter forceps, allowing visualization of the cochlea. The lateral wall of the cochlea was penetrated with a 0.024-in. wire gauge drill bit and endolymph was suctioned from the cochlea. A 5-mm piece of 3-O silk suture, inserted into the cochlear opening, maintained patency. Appraisal of the reliability and standardization of the procedure was performed utilizing startleometry. Histology assessed completeness of the procedure and any evidence of cochlear infection.

On the use of bisection procedures in animal psychophysical scaling

The ability of bisection procedures to specify the form of the psychophysical scale depends upon the precision of the technique. It is demonstrated that the precision of bisection techniques is a function of the stimulus interval bisected. Consequently, the choice of stimuli in a bisection experiment may predispose the ability of the experiment to distinguish between alternative psychophysical scales. The testing of interval scale properties of derived scales and the assessment of context effects in bisection experiments was also discussed.

Memory Consolidation In The Rat Following High-peak Power Pulsed Microwave Irradiation

Water-deprived rats were trained in a single trial to find water in one arm of a Y-maze. Immediately following training rats were either exposed to high-peak power microwave pulses (200 pulses, 80 ns width, 700 megawatts or 700 kilowatts) or returned to their cages. Reliable differences were found between groups in errors made on a 24-h retention test in the Y-maze.

Food Demand And Circadian Rhythmicity Following High-peak Power Pulsed Microwave Irradiation

Rats were either exposed to high-peak power microwave (HPPM) pulses (400 pulses, 80 ns width, 700 megawatts or 700 kilowatts) or were placed in the exposure chamber for an equivalent period of time. Immediately thereafter, the rats were placed in home cages equipped with response levers and pellet dispensers. Rats could press the lever to obtain food pellets, which were their only source of food. Each day the number of lever presses required to obtain a single food pellet (the price of food) was increased. The demand for food (consumption as a function of price) was not affected by microwave exposure, but the circadian pattern of food intake was affected.