Researchers investigating instrumental or operant conditioning in animals have constructed a wide variety of experimental equipment to arrange consequences for responding in controlled laboratory environments. Operant conditioning chambers, or "Skinner boxes," were devised so that experimenters could repeatedly deliver reinforcers following behavior without having to handle the animal trial after trial. An animal can activate one or more response devices inside the chamber, and the researcher can present reinforcement (e.g., food) or punishment (e.g., shock) to the animal inside the box, contingent on the response being made. The operant chamber has also been used to explore a broad range of issues in the stimulus control of behavior with what are called discriminated operants. Here, different discriminative stimuli, such as two differently colored pecking keys displaying white lines of two different orientations, are presented, and the animal is required to respond differently depending on the stimuli. These kinds of visual stimuli have been effectively used to examine such issues as associative competition (Reynolds, 1961), peak shift (Purtle, 1973), and memory (Blough, 1959) in animals.Although researchers investigating instrumental learning continue to rely heavily on the "traditional" Skinner box for experimentation, improvements in a number of technologies have considerably broadened the types of studies that can be conducted with the operant chamber. As well, over the past 3 decades, the nature of the stimulus information that experimenters have presented to animals in the operant chamber has become increasingly complex, due to advances in technology and to the expanding of researchers' interests to include issues related to animal perception and cognition (Fetterman, 1996;Wasserman, 1993).So, although traditional operant chambers continue to be useful, the stimulus information that is presented and the responses that are required of animals are becoming increasingly complex. Researchers of today and tomorrow will need a tool that is (1) powerful enough to probe sensitively into the perceptual and cognitive processes of animals, (2) inexpensive, so that many scientists can use the device, (3) flexible, so that it can be used to investigate a large variety of perceptual and cognitive issues, and (4) easy to construct and to use. Here, we report recent work whose aim was to develop an operant chamber that meets these criteria and that incorporates recent advances in computer technology. We hope that this report might be helpful both to beginning researchers in animal learning and behavior, who may be establishing an operant laboratory, and to more established researchers contemplating an update of their current operant technology. OverviewThe operant system consisted of five Apple eMac computers and four operant chambers, along with supporting hardware and software. Four of the eMac computers independently controlled the experimental sessions in each of the four operant chambers (Figure 1). The fifth eMac s...

A digital interface to support the SKED software system in recent versions of the PDP-8 computer. One printed circuit card of interface logic and optical isolators can be installed in the OMNIBUS to provide 24 input and 36 output lines to external panels containing input simulation switches and input or output indicators.

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A programmable sine-wave generator has been developed that permits microcomputer control of both discrete and continuous variations in the frequency and amplitude of auditory, visual, or vibrotactile stimuli. The function and design of the sine-wave generator as a peripheral to the Apple IIIFffiST system are detailed. Moreover, adaptations of the basic sine-wave circuit are briefly described for interfacing it with other microcomputers (e.g., the IBM PC and compatibles), and for altering the waveform, range, and resolution of the output. Sample programs in Apple IIIFffiST and Applesoft BASIC for controlling signal frequency and amplitude are used to illustrate the simplicity of programmable control. The sine-wave generator has many of the capabilities of commercially available ones, at a fraction of the cost.The purpose of the present paper is to report the development of a sine-wave generator capable of providing both between-and within-trial changes in the frequency and intensity of visual, auditory, and vibrotactile stimuli. The function and design of the sine-wave generator as a peripheral device for the Apple WFIRST system (MarshallGoodell & Gormezano, 1985;Scandrett & Gormezano, 1980) will be detailed. Adaptations of the basic sine-wave circuit will be briefly described for interfacing with other microcomputers (e.g., IBM PC and compatibles), and for altering the waveform, range, and resolution of the output. Sample programs in Apple II1FIRST and Applesoft BASIC for controlling signal frequency and amplitude will be provided to illustrate the simplicity of programmable control with the sine-wave generator. Lastly, the power and flexibility of the sine-wave generator will be compared to that of more expensive commercial systems. THE SINE-WAVE GENERATOR Functional CharacteristicsThe sine-wave generator, under control of the Apple IIJ FIRST system, regulates changes in stimulus frequency and amplitude over time, using digital-to-analog (OJA) converters and a voltage-controlled function generator. Separate OJA converters control 256 levels of sine-wave frequency and amplitude, respectively. Selection among the available frequency and amplitude levels is made within a microcomputer control program that sends separate 8-bit digital codes to each OJA converter. Each time an 8-bit code is received by the OJA converter, the digi11ris research was supported by grants from the National Science Foundation and the University of Iowa Foundation (through the generous contributions of H. Gormezano, S. L. Nusser, and W. G. Nusser). Requests for reprints should be sent to I. Gormezano, Department of Psychology, University of Iowa, Iowa City, IA 52242. tal input is translated (within 160 nsee) to the corresponding output voltage, and the selected output setting is latched until another control code is received. Although it is possible to use OJA converters alone to directly generate complex waveforms (e.g., speech), the addition of a voltage-controlled function generator simplifies the production of standard waveforms by sub...