Achromatopsia: a Failure to Perceive Color (The World Appears in Grayscale), Not to Be

Achromatopsia: A failure to perceive color (the world appears in grayscale), not to be confused with color blindness (e.g. in which red and green cannot be discriminated).
Action potential: A sudden change (depolarization and repolarization) in the electrical properties of the neuron membrane in an axon.
Activation: An increase in physiological processing in one condition relative to some other condition(s).
Additive factors method: A general method for dividing reaction times into different stages devised by Sternberg.
Afferent dysgraphia: Stroke omissions and additions in writing that may be due to poor use of visual and kinesthetic feedback.
Affordances: Structural properties of objects imply certain usages.
Agrammatism: Halting, “telegraphic” speech production that is devoid of function words (e.g. of, at, the, and), bound morphemes (e.g. –ing, –s) and often verbs.
Akinetopsia: A failure to perceive visual motion.
Allele: Different versions of the same gene.
Allocentric space: A map of space coding the locations of objects and places relative to each other.
Allograph: Letters that are specified for shape (e.g. case, print versus script).
Allophones: Different spoken/acoustic renditions of the same phoneme.
Amodal: Not tied to one or more perceptual systems.
Amusia: An auditory agnosia in which music perception is affected more than the perception of other sounds.
Amygdala: Part of the limbic system; implicated in detecting fearful stimuli.
Aneurysm: Over-elastic region of artery that is prone to rupture.
Anomia: Word-finding difficulties.
Anterior: Towards the front.
Anterograde memory: Memory for events that have occurred after brain damage.
Apperceptive agnosia: A failure to understand the meaning of objects due to a deficit at the level of object perception.
Apraxia for speech: Difficulties in shaping the vocal tract.
Articulatory loop: A short-term memory store for verbal material that is refreshed by subvocal articulation.
Articulatory suppression: Silently mouthing words while performing some other task (typically a memory task).
Asperger syndrome: Autism with no significant delay in early language and cognitive development.
Associative agnosia: A failure to understand the meaning of objects due to a deficit at the level of semantic memory.
Associative priming: Reaction times are faster to a stimulus if that stimulus is preceded by a stimulus of similar meaning (this is also known as semantic priming).
Attention: The process by which certain information is selected for further processing and other information is discarded.
Attentional dyslexia: An inability to report the constituent letters of words that can be read (together with intact reading of isolated letters).
Auditory stream segregation: The division of a complex auditory signal into different sources or auditory objects.
Autism: The presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activities and interests.
Autotopagnosia: An inability to localize body parts on oneself, on pictures or on others.
Axon: A branching structure that carries information to other neurons and transmits an action potential.
Balint’s syndrome: A severe difficulty in spatial processing normally following bilateral lesions of parietal lobe; symptoms include simultanagnosia, optic ataxia and optic apraxia.
Basal ganglia: Regions of subcortical gray matter involved in aspects of motor control and skill learning; they consist of structures such as the caudate nucleus, putamen and globus pallidus.
Basilar membrane: A membrane within the cochlea containing tiny hair cells linked to neural receptors.
Behavioral genetics: A field concerned with studying the inheritance of behavior and cognition.
Behavioral neuroscience: Cognitive neuroscience in non-human animals.
Belt region: Part of secondary auditory cortex.
Biological motion: The ability to detect whether a stimulus is animate or not from movement cues alone.
Blind spot: The point at which the optic nerve leaves the eye. There are no rods and cones present there.
Blindsight: A symptom in which the patient reports not being able to consciously see stimuli in a particular region but can nevertheless perform visual discriminations (e.g. long, short) accurately.
Block design: Stimuli from a given condition are presented consecutively together.
BOLD: Blood oxygen-level-dependent contrast; the signal measured in fMRI that relates to the concentration of deoxyhemoglobin in the blood.
Broca’s aphasia: A type of aphasia traditionally associated with damage to Broca’s area and linked to symptoms such as agrammatism and articulatory deficits.
Brodmann’s areas: Regions of cortex defined by the relative distribution of cell types across cortical layers (cytoarchitecture).
Cancellation task: A variant of the visual search paradigm in which the patient must search for targets in an array, normally striking them through as they are found.
Capgras syndrome: People report that their acquaintances (spouse, family, friends and so on) have been replaced by “body doubles”.
Categorical perception: Continuous changes in input are mapped on to discrete percepts.
Category specificity: The notion that the brain represents different categories in different ways (and/or different regions).
Cell body: Part of the neuron containing the nucleus and other organelles.
Central dyslexia: Disruption of reading arising after computation of a visual word form (e.g. in accessing meaning, or translating to speech).
Cerebellum: Structure attached to the hindbrain; important for dexterity and smooth execution of movement.
Change blindness: Participants fail to notice the appearance/disappearance of objects between two alternating images.
Chromosome: An organized package of DNA bound up with proteins; each chromosome contains many genes.
Co-articulation: The production of one phoneme is influenced by the preceding and proceeding phonemes.
Cochlea: Part of the inner ear that converts liquid-borne sound into neural impulses.
Cognition: A variety of higher mental processes such as thinking, perceiving, imagining, speaking, acting and planning.
Cognitive neuropsychology: The study of brain-damaged patients to inform theories of normal cognition.
Cognitive neuroscience: Aims to explain cognitive processes in terms of brain-based mechanisms.
Cognitive subtraction: A type of experimental design in functional imaging in which activity in a control task is subtracted from activity in an experimental task.
Cohort model: In lexical access, a large number of spoken words are initially considered as candidates but words get eliminated as more evidence accumulates.
Color constancy: The color of a surface is perceived as constant even when illuminated in different lighting conditions.
Complex cells: In vision, cells that respond to light in a particular orientation but do not respond to single points of light.
Conditioned taste aversion: A highly durable avoidance of food that has previously been associated with sickness.
Cone cells: A type of photoreceptor specialized for high levels of light intensity, such as those found during the day, and specialized for the detection of different wavelengths.
Confabulation: A memory that is false and sometimes self-contradictory without an intention to lie.
Consolidation: The process by which moment-to-moment changes in brain activity are translated into permanent structural changes in the brain.
Constructive memory: The act of remembering construed in terms of making inferences about the past, based on what is currently known and accessible.
Contention scheduling: The mechanism that selects one particular schema to be enacted from a host of competing schemas.
Corpus callosum: A large white matter tract that connects the two hemispheres.
Counting: The process of putting each item in a collection in one-to-one correspondence with a number or some other internal/external tally.
Critical period: A time window in which appropriate environmental input is essential for learning to take place.
Cross-modal perception: Integrating information across sensory modalities.
Deactivation: A decrease in physiological processing in one condition relative to some other condition(s).
Deception: A situation in which outward behavior deliberately contradicts inner knowledge and beliefs.
Declarative memory: Memories that can be consciously accessed.
Deep dyslexia: Real words are read better than non-words and semantic errors are made in reading.
Deep dysphasia: An inability to repeat non-words and the producion of semantic errors in word repetition.
Degrees of freedom problem: There are potentially an infinite number of motor solutions for acting on an object.
Delusions: Fixed beliefs that are false or fanciful (e.g. of being persecuted).
Dendrites: Branching structures that carry information from other neurons.
Diaschisis: A discrete brain lesion can disrupt the functioning of distant brain regions that are structurally intact.
Diffusion tensor imaging (DTI): Uses MRI to measure white matter connectivity between brain regions.
Dipole modeling: An attempt to solve the inverse problem in ERP research that involves assuming how many dipoles (regions of electrical activity) contribute to the signal recorded at the scalp.
Directed forgetting: Forgetting arising because of a deliberate intention to forget.
Distance effect: It is harder to decide which of two numbers is larger when the distance between them is small (e.g. 8–9 relative to 2–9).
Domain-specificity: The idea that a cognitive process (or brain region) is dedicated solely to one particular type of information (e.g. colors, faces, words).
Dopamine: A neurotransmitter with important roles, including in reward, motivation, attention and learning.
Dorsal: Towards the top.
Double dissociation: Two single dissociations that have a complementary profile of abilities.
Dual-aspect theory: The belief that mind and brain are two levels of description of the same thing.
Dualism: The belief that mind and brain are made up of different kinds of substance.
Dual-task interference: If there is a decrement in performance associated with doing two things at once, it suggests that these two tasks share cognitive processes.
Duchenne lines: Wrinkles around the eyes associated with a sincere smile.
Dysarthria: Impaired muscular contractions of the articulatory apparatus.
Dyscalculia: Difficulties in understanding numbers; calculation difficulties.
Dysgraphia: Difficulties in spelling and writing.
DZ twins (dizygotic): Twins who share half of their genes, caused when two eggs are fertilized by two different sperm.
Early selection: A theory of attention in which information is selected according to perceptual attributes.
Ecological validity: The extent to which a task relates to everyday situations outside of the laboratory.
efMRI: Event-related functional magnetic resonance imaging.
Egocentric space: A map of space coded relative to the position of the body.
Emotion: States/processes that prepare the organism for certain behaviors, particularly those with survival value.
Empathy: The ability to appreciate others’ points of view and share their experiences.
Empiricism: In philosophy, the view that the newborn mind is a blank slate.
Encoding specificity hypothesis: Events are easier to remember when the context at retrieval is similar to the context at encoding.
Endogenous: Related to properties of the task.
Endogenous orienting: Attention is guided by the goals of the perceiver.
Episodic memory: Memory of specific events in one’s own life.
Error-related negativity: An electrical potential (“error potential”) that can be detected at the scalp when an error is made.
Event-related design: Stimuli from two or more conditions are presented randomly or interleaved.
Excitation: An increase of the activity of a brain region (or a cognitive process), triggered by activity in another region/process.
Executive functions: Control processes that enable an individual to optimize performance in situations requiring the operation and coordination of several more basic cognitive processes.
Exogenous: Related to properties of the stimulus.
Exogenous orienting: Attention that is externally guided by a stimulus.
Explicit memory: See declarative memory.
Extinction: When presented with two stimuli at the same time (one in each hemispace), then the stimulus on the opposite side of the lesion is not consciously perceived.

Face recognition units (FRUs): Stored knowledge of the three-dimensional structure of familiar faces.
False belief: A belief that differs from one’s own belief and that differs from the true state of the world.
False memory: A memory that is either partly or wholly inaccurate but is accepted as a real memory by the person doing the remembering.
Familiarity: Context-free memory in which the recognized item just feels familiar.
Figure–ground segregation: The process of segmenting a visual display into objects versus background surfaces.
Filial imprinting: The process by which a young animal comes to recognize the parent.
Finger agnosia: An inability to identify individual fingers by touch.
Fixation: A stationary pause between eye movements.
Formants: Horizontal stripes on the spectrogram produced with a relative free flow of air (e.g. by vowels).
Forward model: A representation of the motor command (a so-called “efference copy”) is used to predict the sensory consequences of an action.
Freudian slip: The substitution of one word for another that is sometimes thought to reflect the hidden intentions of the speaker.
Frontal apraxia: Failure in tasks of routine activity that involve setting up and maintaining different subgoals, but with no basic deficits in object recognition or gesturing the use of isolated objects (also called action disorganization syndrome).
Frontal eye fields: Responsible for voluntary movement of the eyes.
Functional imaging: Measures temporary changes in brain physiology associated with cognitive processing; the most common methods of PET and fMRI are based on a hemodynamic measure.
Functional integration: The way in which different regions communicate with each other.
Functional specialization: Different regions of the brain are specialized for different functions.
Fundamental frequency: The lowest frequency component of a complex sound that determines the perceived pitch.
Garden-path sentences: A sentence in which the early part biases a syntactic interpretation that turns out to be incorrect.
Gene X–environment interactions: Susceptibility to a trait depends on a particular combination of a gene and environment.
Gene–environment correlations: Genetic influences in people’s exposure to different environments.
Gerstmann’s syndrome: A set of four deficits believed to be associated with damage to the left parietal lobe (acalculia, finger agnosia, agraphia and left–right disorientation).
Glia: Support cells of the nervous system involved in tissue repair and in the formation of myelin (amongst other functions).
Grandmother cell: A hypothetical neuron that just responds to one particular stimulus (e.g. the sight of one’s grandmother).
Graph: Letters that are specified in terms of stroke order, size and direction.
Grapheme: An abstract description that specifies letter identity.
Graphemic buffer: A short-term memory component that maintains a string of abstract letter identities while output processes (for writing, typing, etc.) are engaged.
Gray matter: Matter consisting primarily of neuronal cell bodies.
Group studies: In neuropsychology, the performance of different patients is combined to yield a group average.
Gyri (gyrus = singular): The raised folds of the cortex.
Habituation: In infant studies, old or familiar objects receive less attention.
Hallucinations: Illusory percepts not shared by others (e.g. hearing voices).
Head-related transfer function (HRTF): An internal model of how sounds get distorted by the unique shape of one’s own ears and head.
Hemianopia: Cortical blindness restricted to one half of the visual field (associated with damage to the primary visual cortex in one hemisphere).
Hemiplegia: Damage to one side of the primary motor cortex results in a failure to voluntarily move the other side of the body.
Hemodynamic response function (HRF): Changes in the BOLD signal over time.
Heritability: The proportion of variance in a trait, in a given population, that can be accounted for by genetic differences amongst individuals.
Homophone: Words that sound the same but have different meanings (and often different spellings); e.g. ROWS and ROSE.
Homunculus problem: The problem of explaining volitional acts without assuming a cognitive process that is itself volitional (“a man within a man”).
Huntington’s disease: A genetic disorder affecting the basal ganglia and associated with excessive movement.
Hypercomplex cells: In vision, cells that respond to particular orientations and particular lengths.
Hyperkinetic: An increase in movement.
Hypokinetic: A reduction in movement.
Hypothalamus: Consists of a variety of nuclei that are specialized for different functions that are primarily concerned with the body and its regulation.
Ideomotor apraxia: An inability to produce appropriate gestures given an object, word or command.
Illusory conjunctions: A situation in which visual features of two different objects are incorrectly perceived as being associated with a single object.
Imitation: The ability to reproduce the behavior of another through observation.
Implicit memory: See non-declarative memory.
Inattentional blindness: A failure to consciously see something because attention is directed away from it.
Inferior: Towards the bottom.
Inferior colliculi: A midbrain nucleus that forms part of a subcortical auditory pathway.
Information processing: An approach in which behavior is described in terms of a sequence of cognitive stages.
Inhibition: A reduction/suppression of the activity of a brain region (or a cognitive process), triggered by activity in another region/process.
Inhibition of return: A slowing of reaction time associated with going back to a previously attended location.
Instinct: A behavior that is a product of natural selection.
Insula: A region of cortex buried beneath the temporal lobes; involved in body perception and contains the primary gustatory cortex; responds to disgust.
Integrative agnosia: A failure to integrate parts into wholes in visual perception.
Interactions: The effect of one variable upon another.
Interactivity: Later stages of processing can begin before earlier stages are complete.
Inverse problem: The difficulty of locating the sources of electrical activity from measurements taken at the scalp (in ERP research).
James–Lange theory: The self-perception of bodily changes produces emotional experience (e.g. one is sad because one cries).