Using a set of six baboons (Papio cynocephalus), we conducted a series of seven experiments designed to evaluate the potentially aversive character of a 60 Hz electric field (EF). Initially, the subjects were trained, using food rewards as the reinforcer, to respond only when a cue light was illuminated. Next, an EF was presented along with the cue light; responses produced delivery of a food pellet and turned off both the cue light and the EF. Then, stimulus and reward conditions were varied. We determined that 1) presence of a strong EF does not affect operant responding for food rewards, 2) subjects will not respond at normal rates when the only reinforcer is termination of a strong EF, 3) presence of a strong EF can serve as a discriminative stimulus, 4) presence of a strong EF does not affect extinction of an appetite-motivated task, and 5) presentation of an EF can become a secondary reinforcer. The pattern of results was consistent across all experiments, suggesting that an EF of as much 65 kV/m is not aversive to nonhuman primates. Separately, we demonstrated that the average EF detection threshold for baboons in 12 kV/m. Thus, EF exposure at intensities well above the detection threshold and at species-scaled EF strengths greater than those found environmentally does not appear to be aversive.

A unique exposure facility was designed and constructed to generate large-scale vertical electric fields (EF) of up to 65 kV/m and horizontal magnetic fields (MF) of up to 100 microT (1G), so that the behavioral and neuroendocrine effects of 60 Hz EF or combined electric and magnetic field (E/MF) exposure could be examined using nonhuman primates as subjects. Facility design and operational problems and their solutions are presented, and representative operational data from four sets of experiments are provided. A specially designed, optically isolated, 4 cm spherical-dipole EF probe and a commercially available MF probe were used to map the EF and MF within the fiberglass animal cages. In addition, amplifiers, signal conditioners, and A/D converters provided EF, MF, and transformer signals to a microcomputer at 15 min intervals. The apparatus produced homogeneous, stable E/MF at the desired intensities, and the fiberglass cages did not produce appreciable distortion or attenuation. Levels of recognized EF artifacts such as corona and ozone were negligible. The facility worked as intended, providing a well-characterized and artifact-controlled environment for experiments with baboons (Papio cynocephalus).

Using a set of six baboons (Papio cynocephalus), we conducted a series of seven experiments designed to evaluate the potentially aversive character of a 60 Hz electric field (EF). Initially, the subjects were trained, using food rewards as the reinforcer, to respond only when a cue light was illuminated. Next, an EF was presented along with the cue light; responses produced delivery of a food pellet and turned off both the cue light and the EF. Then, stimulus and reward conditions were varied. We determined that 1) presence of a strong EF does not affect operant responding for food rewards, 2) subjects will not respond at normal rates when the only reinforcer is termination of a strong EF, 3) presence of a strong EF can serve as a discriminative stimulus, 4) presence of a strong EF does not affect extinction of an appetite‐motivated task, and 5) presentation of an EF can become a secondary reinforcer. The pattern of results was consistent across all experiments, suggesting that an EF of as much 65 kV/m is not aversive to nonhuman primates. Separately, we demonstrated that the average EF detection threshold for baboons is 12 kV/m. Thus, EF exposure at intensities well above the detection threshold and at species‐scaled EF strengths greater than those found environmentally does not appear to be aversive. © 1996 Wiley‐Liss, Inc.

In two separate experiments, we examined the effects of a 60 Hz electric field (EF) on performance of an operant schedule consisting of two signaled components: fixed-ratio (FR30) and differential reinforcement of low-rate (DRL20). In each experiment, 12 naive baboons (Papio cynocephalus) were assigned randomly to either an EF-exposed experimental group or a sham-exposed control group. A homogeneous vertical EF of 30 kV/m was used in one experiment; 60 kV/m was used in the other. The experimental design for both experiments included 6 week preexposure, exposure, and postexposure periods. The planned analyses indicated no evidence of statistically significant (P < .05) effects of EF exposure. However, exploratory analyses comparing performance during the last week of preexposure and the first week of exposure revealed statistically significant acute effects (work stoppage): The mean response rates of the EF-exposed groups were greatly reduced on day 1 of exposure but were normal by the end of day 2 of EF exposure. We hypothesize that introduction of a highly unusual stimulus, the EF, temporarily interfered with normal operant behavior to produce a primary work stoppage. Supplementary cross-over experiments added at the end of each main experiment indicated that work stoppage occurred again when formerly EF-exposed subjects served as sham-exposed controls, while other subjects received their first EF exposure. Presumably, reoccurrence of other stimuli correlated with initial exposure to the EF became sufficient to subsequently cause secondary work stoppage in the absence of direct EF exposure. The primary and secondary work-stoppage effects were reproducible.

In two separate experiments, we examined the effects of a 60 Hz electric field (EF) on performance of an operant schedule consisting of two signaled components: fixed‐ratio (FR30) and differential reinforcement of low‐rate (DRL20). In each experiment, 12 naive baboons (Papio cynocephalus) were assigned randomly to either an EF‐exposed experimental group or a sham‐exposed control group. A homogeneous vertical EF of 30 kV/m was used in one experiment; 60 kV/m was used in the other. The experimental design for both experiments included 6 week preexposure, exposure, and postexposure periods. The planned analyses indicated no evidence of statistically significant (P < .05) effects of EF exposure. However, exploratory analyses comparing performance during the last week of preexposure and the first week of exposure revealed statistically significant acute effects (work stoppage): The mean response rates of the EF‐exposed groups were greatly reduced on day 1 of exposure but were normal by the end of day 2 of EF exposure. We hypothesize that introduction of a highly unusual stimulus, the EF, temporarily interfered with normal operant behavior to produce a primary work stoppage. Supplementary cross‐over experiments added at the end of each main experiment indicated that work stoppage occurred again when formerly EF‐exposed subjects served as sham‐exposed controls, while other subjects received their first EF exposure. Presumably, reoccurrence of other stimuli correlated with initial exposure to the EF became sufficient to subsequently cause secondary work stoppage in the absence of direct EF exposure. The primary and secondary work‐stoppage effects were reproducible. © 1996 Wiley‐Liss, Inc.