A procedure was used where responses by a pigeon produced electric shock both to that pigeon (response-dependent shock) and to another pigeon (response-independent shock) working under the same schedule of food presentation. Both response-dependent and response-independent shock partially suppressed responding. Pentobarbital, chlordiazepoxide and ethanol increased responding suppressed by response-dependent shock, but only pentobarbital increased responding suppressed by response-independent shock. Morphine, d-amphetamine, chlorpromazine, doxepin, and pentazocine either had no effect, or further decreased rates of responding suppressed by response-dependent or response-independent shock.