Object permanence The recognition that objects exist independently of an individual's action or awareness; an important cognitive acquisition of infancy.
Object relations theory Psychoanalytic theory that originated with Melanie Klein's view that the building blocks of how people experience the world emerge from their relations to loved and hated objects (significant people in their lives).
Observational learning The process of learning new responses by watching the behavior of another.
Observer bias The distortion of evidence because of the personal motives and expectations of the viewer.
Obsessive-compulsive disorder (OCD) A mental disorder characterized by obsessions-recurrent thoughts, images, or impulses that recur or persist despite efforts to suppress them-and compulsions-repetitive, purposeful acts performed according to certain rules or in a ritualized manner.
Occipital lobe Rearmost region of the brain; contains primary visual cortex.
Olfactory bulb The center where odor-sensitive receptors send their signals, located just below the frontal lobes of the cortex.
Operant Behavior emitted by an organism that can be characterized in terms of the observable effects it has on the environment.
Operant conditioning Learning in which the probability of a response is changed by a change in its consequences.
Operant extinction When a behavior no longer produces predictable consequences, its return to the level of occurrence it had before operant conditioning.
Operational definition A definition of a variable or condition in terms of the specific operation or procedure used to determine its presence.
Opponent-process theory The theory that all color experiences arise from three systems, each of which includes two "opponent" elements (red versus green, blue versus yellow, and black versus white).
Optic nerve The axons of the ganglion cells that carry information from the eye toward the brain.
Organismic variables The inner determinants of an organism's behavior.
Organizational psychologists Psychologists who study various aspects of the human work environment, such as communication among employees, socialization or enculturation of workers, leadership, job satisfaction, stress and burnout, and overall quality of life.
Orientation constancy The ability to perceive the actual orientation of objects in the real world despite their varying orientation in the retinal image.
Out-groups The groups with which people do not identify.
Overregularization A grammatical error, usually appearing during early language development, in which rules of the language are applied too widely, resulting in incorrect linguistic forms.