Encyclopedia of Psychology and Law

Symptoms related to thought form include loose

associations (jumping quickly from topic to topic), tan-

gentiality (keeps wandering off the topic), circumstan-

tiality (speech is only indirectly relevant to the topic

being discussed), derailment (loses track of the topic

completely), perseveration (keeps returning to the same

topic), thought blocking (abruptly stops talking), neol-

ogisms (makes up new words), clanging (speech is full

of rhymes), pressured speech (talks quickly and loudly),

incoherence (speech is unintelligible), and echolalia

(repeating words spoken by others).

Disturbances of Perception.These also can be divided

into two major types. First, hallucinations are sensa-

tions in the absence of an external stimulus. They may

occur in any sensory modality. The most common are

auditory (e.g., hearing voices that other people can’t

hear, often several people conversing in negative

terms with or about the person or telling the person

what to do) and visual (e.g., seeing things that other

people can’t see, such as lurking strangers, ghosts, or

visions). Second, depersonalization and derealization

are abnormalities in perception of self and the envi-

ronment, respectively. Depersonalization often

involves “out-of-body” experiences (e.g., people per-

ceive that their minds have left their bodies and are

floating around the room or that they no longer have

control over the movement of their own bodies).

Derealization, in contrast, often involves the percep-

tion that the outside world is unreal or a sham (e.g.,

other people are automatons).

Disturbances of Emotion. These involve either the

absence of normal affect or the presence of abnormal

affect. Symptoms of the first type include blunted

affect or poverty of affect (a restricted range and depth

of emotional displays), anhedonia (loss of feelings of

pleasure), and flat affect (near-complete absence of

emotion). Symptoms of the second type include per-

plexity (confusion or uncertainty about what is going

on), stormy affect (intense and labile emotions),

incongruity (emotional displays that are apparently

opposite to the tone of the topic being discussed), and

silly affect (emotional displays that are unrelated to

the topic being discussed and are often perceived as

immature or juvenile).

Disturbances of Volition. These involve difficulties

with voluntary, purposive behavior. Symptoms related

to problems making plans and carrying out goal-directed

activity include abulia or avolition (inactivity), apathy

(ambivalence or loss of interest), anergia (loss of

energy), autism or social withdrawal (failure to inter-

act with other people), self-neglect (neglect of one’s

own health and hygiene), negativism (ignoring the

directions of others, resisting attempts to be moved by

maintaining a rigid posture), and alogia or mutism

(not speaking at all). Symptoms related to disturbance

of behavioral tone, also known as catatonic symptoms,

include hypertonia (overactivity, such as moving a lot

or moving quickly) and hypotonia or catalepsy

(underactivity, such as moving rarely, moving slowly,

and waxy flexibility). Disturbances of purposeful

activity include mannerisms (strange gestures or

movements, such as walking on tiptoe or wiggling the

fingers), stereotypies (repetitive, tic-like movements

or vocalizations, such as constantly rubbing one’s

head or barking like a dog), grimaces, posturing (assum-

ing strange poses, such as standing with one leg in the

air or sitting with arms extended), echopraxia (repeat-

ing the movements of others), and bizarre behavior

(e.g., masturbating in public, eating inedible substances,

playing with feces).

Symptom Clusters.Clinical observation and research

have found that certain psychotic symptoms fre-

quently co-occur. There are at least three distinct

syndromes (i.e., symptom clusters). Positive symp-

tomsare pathological by their presence—things such

as delusions, hallucinations, stormy affect, and man-

nerisms. Negative symptoms are pathological by

their absence; examples are poverty of speech,

poverty of affect, and social withdrawal. Disorgani-

zation symptomsreflect impairment in the regulation

or coordination of basic psychological functions—

for example, incoherence, silly affect, and bizarre

behavior.

Contemporary Classification

The classification of psychotic disorders is based on

symptomatology, course, and etiology. In the fourth

edition of the American Psychiatric Association’s

Diagnostic and Statistical Manual of Mental Disorders,

or DSM-IV,psychotic disorders are grouped under the

heading “Schizophrenia and Other Psychotic Disorders”

and comprise a number of specific conditions.

Schizophrenia is characterized by a progressive or

insidious onset (the prodromal phase), during which

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