O O data O variable O-X-O O’Connor v. Donaldson O&M OA OAEs Obamacare obedience obesity object Object Assembly test object cathexis object choice object color object constancy object display object identity object language object learning object libido object loss object love object of consciousness object of instinct object permanence object play object relations object relations psychotherapy object relations theory object-based attention object-location memory object-superiority effect objectification objective objective anxiety objective competitive situation objective elaboration objective indicator objective prior objective psychology objective psychotherapy objective reality objective reference objective responsibility objective scoring objective self-awareness objective set objective test objectivism objectivity objectivity illusion obligate carrier obligation schema oblique oblique rotation OBM obnubilation obscenity obscurantism observation observation coding system observation delusion observation hold observational learning observational study observed variable observed-score equating observer observer bias observer drift observer memory observing response obsession obsessional type obsessive behavior obsessive-compulsive disorder (OCD) obsessive-compulsive personality disorder obstruction method obstructive hydrocephalus obstructive sleep apnea obstruent obtrusive idea obturator OCB Occam’s razor occasion setter occasion setting occasional cause occasionalism occipital cortex occipital lobe occlusion occult occupation occupational ability occupational adjustment occupational analysis occupational biomechanics occupational counseling occupational cramp occupational culture occupational disease occupational ergonomics occupational health psychology occupational interest measure occupational neurosis occupational norm occupational psychology occupational rehabilitation Occupational Safety and Health Administration (OSHA) occupational segregation occupational status occupational stress occupational test occupational therapy (OT) OCD oceanic feeling oceanic state octave octave effect ocul- ocular ocular accommodation ocular apraxia ocular dominance ocular dominance column ocular dominance histogram ocular dysmetria ocular flutter ocular hypertelorism ocular myopathy ocular palsy ocular pursuit oculo- (ocul-) oculocerebral-hypopigmentation syndrome oculocerebrorenal syndrome oculogravic illusion oculogyral illusion oculogyric crisis oculomotor apraxia oculomotor changes oculomotor nerve oculomotor nucleus oculomotor palsy oculosympathetic paralysis oculovestibular response Od OD odd–even reliability oddity from sample oddity problem odds odds ratio (OR) odor odor prism odorant odorant-binding protein odorimetry odorvector Odyle oedipal conflict oedipal phase Oedipus complex OEP OFA off cells (OFF cells) off response (OFF response) off-center bipolar cell off-center ganglion cell off-center/on-surround off-label off-the-job training off-time life events officer selection officer training officer-assisted suicide offline group ogive Ohm’s law oikofugic oikomania oikotropic OKR olan olanzapine old-fashioned racism old-old Older Adult Resources and Services oldest old Oleptro olfactie olfaction olfactometer olfactometry olfactophilia olfactorium olfactory adaptation olfactory area olfactory brain olfactory bulb olfactory cell olfactory cilium olfactory cortex olfactory cross-adaptation olfactory dysfunction olfactory encoding olfactory epithelium olfactory eroticism olfactory evoked potential (OEP) olfactory hallucination olfactory mucosa olfactory nerve olfactory receptor olfactory reference syndrome olfactory sense organ olfactory stimulation olfactory sulcus olfactory system olfactory tract olfactory transduction olfactory tubercle oligarchy oligo- (olig-) oligodendrocyte oligodendroglioma oligohydramnios oligospermia olisbos olivary nucleus Oliver–McFarlane syndrome olivocochlear bundle olivopontocerebellar atrophy ololiuqui OLS OLSAT ombudsman omega squared omen omission training omitted variable bias omnibus test omnipotence omnipotent therapist on cells (ON cells) on response (ON response) on-center bipolar cell on-center ganglion cell on-center/off-surround on-the-job training on-time life events on–off cell onanism oncology ondansetron one-factor analysis of variance one-group pretest–posttest design one-parameter model one-person psychology one-sample t test one-sample test one-shot case study one-sided message one-tailed hypothesis one-tailed test one-trial learning one-way analysis of covariance one-way analysis of variance one-way design one-word stage oneirism oneiro- (oneir-) oneirodynia oneiromancy oneirophrenia oniomania online group online self-help group online social network online therapy onomatopoeia onset insomnia onset of action ontoanalysis ontogenetic fallacy ontogenetic psychology ontogeny ontogeny of conscious experience ontological confrontation ontology oocyte oogenesis oophorectomy opaque open adoption open call system open class society open design open economy open group open head injury open hospital open marriage open question open shop open skill open society open study open system open system theory open ward open word open-class words open-classroom design open-classroom method open-door hospital open-ended interview open-field chamber open-field test open-label study open-loop system open-office design opening technique openmindedness openness to experience operandum operant operant behavior operant chamber operant conditioning operant conditioning chamber operant conditioning therapy operant learning operant level operant paradigm operant response operation operation span (OSpan) operational analysis operational definition operational research operational sex ratio operational thought operationalism operationism operationist view of consciousness operations research operative knowledge operators ophidiophilia ophidiophobia ophthalmia ophthalmic nerve ophthalmology ophthalmometer ophthalmoplegia ophthalmoplegia externa ophthalmoscope opiate opinion opinion leader opinion survey opinion testimony opinionnaire opioid opioid abuse opioid agonist opioid analgesic opioid antagonist opioid blockade opioid dependence opioid intoxication opioid neurotransmitter opioid receptor opioid system opioid use disorder opioid withdrawal Opitz G/BBB syndrome opium opponent cell opponent process theory of acquired motivation opponent process theory of color vision opportunism opportunity class opportunity sampling opportunity structure opposites test oppositional defiant disorder opsin opt- optic aphasia optic apraxia optic array optic ataxia optic atrophy optic chiasm optic disk optic flow optic nerve optic neuritis optic radiations optic tectum optic tract optical axis optical defect optical flow pattern optical illusion optical projection optical scanner optician optics optimal adjustment optimal apparent motion optimal arousal theory optimal design optimal distinctiveness theory optimal foraging theory optimal functioning optimal level optimal outbreeding optimal scaling optimal stimulation principle optimism optimization optimize opto- (opt-) optogram optokinetic effect optokinetic reflex (OKR) optometry OR or rule or- ora serrata oral administration oral behavior oral character oral coitus oral contraceptive oral eroticism oral gratification oral history oral method oral personality oral phase oral sadism oral sex oral sound oral stage oral-aggressive personality oral-biting phase oral-receptive personality oral-sadistic phase oral-sucking phase oral–genital contact oral–lingual dyskinesia oral–motor feeding problem Oralet oralism orality Orap Orbison illusion orbitofrontal cortex orchidectomy order order effect order of magnitude ordered scale orderliness ordinal ordinal data ordinal scale ordinal variable ordinality ordinary creativity ordinary least squares regression ordinate Orestes complex orexin orexis organ inferiority organ language organ of Corti organ speech organelle organic organic amnesia organic approach organic defect organic disorder organic hallucinations organic paralysis organic retardation organic selection organic sensation organic therapies organic variable organicism organicity organicity test organism organismic organismic model organismic personality theory organismic psychology organismic valuing process organismic variable organization organizational approach organizational assessment organizational behavior management (OBM) organizational career organizational citizenship behavior (OCB) organizational climate organizational commitment organizational culture organizational culture analysis organizational development (OD) organizational dynamics organizational effect organizational effectiveness organizational efficiency organizational hierarchy organizational hypothesis organizational identification organizational justice organizational politics organizational psychology organizational structure organized offender organogenesis organum vasculosum of the lamina terminalis (OVLT) orgasm orgasmic dysfunction orgasmic phase orgasmic platform orgasmic reconditioning orgastic potency orgone orgone therapy orgy oriental nightmare-death syndrome orientation orientation and mobility training (O＆M training) orientation column orientation illusion orienting response origin-of-language theory original cause original sin originality Orne effect ornithinemia oro- (or-) orofacial apraxia orofacial dyskinesia orogenital activity oropharynx orphanin FQ orphenadrine Ortgeist orthergasia ortho- (orth-) Ortho-Rater orthodox psychoanalysis orthodox sleep orthogenesis orthogenetic principle orthogonal orthogonal coding orthogonal contrast orthogonal design orthogonal rotation orthographic distinctiveness effect orthography orthokinesis orthomolecular medicine orthonasal olfaction orthopedic cane orthopsychiatry orthoptics orthoptoscope orthorexia nervosa orthostatic hypotension orthotics oscillator circuit oscillatory interference model oscillograph oscillometer oscillopsia oscilloscope OSHA osmolagnia osmolarity osmometer osmometric thirst osmoreceptor osmoregulation osmosis osmotic pressure OSpan osphresiolagnia osphresiophilia osseous labyrinth ossicles osteomalacia osteopathy osteopetrosis osteoporosis ostracism Ostwald color system OT ot- OTC Othello syndrome other-directed other–total ratio (OTR) otic Otis–Lennon School Ability Test (OLSAT) otitis media oto- (ot-) otoacoustic emissions (OAEs) otoconium otohemineurasthenia otolaryngology otolith otology otoneurology otopalatodigital spectrum disorders otosclerosis ototoxic OTR ought self Ouija board out-of-body experience outbreeding outcome outcome dependence outcome evaluation outcome expectancies outcome interdependence outcome measures outcome research outcome variable outer ear outer hair cells outer nuclear layer outer plexiform layer outer psychophysics outer-directed outercourse outgroup outgroup extremity effect outgroup homogeneity bias outing outlier outpatient outpatient commitment outpatient services outplacement counseling output output interference outreach ova oval window ovarian follicle ovariectomy ovary over-the-counter (OTC) overachiever overactivity overage overattribution bias overbreathing overclassification overcompensation overconfidence overcontrolled overcorrection overcrowding overdetermination overdispersion overdose (OD) Overeaters Anonymous (OA) overexpectation overextension overgeneralization overheating overidentification overinclusion overintensity overjustification effect overlapping psychological tasks overlapping waves theory overlearning overload overload principle overmatching overmedication overpayment inequity overpopulation overproduction overprotection overreaction overregularization oversampling overshadowing overshoot overshooting overstaffing overt overt behavior overt homosexuality overt integrity test overt response overtone overtraining syndrome overvalued idea overweight oviduct oviparity OVLT ovulation ovulatory cycle ovum oxazepam oxidation oxycephaly oxycodone oxytocic oxytocin