Developmental psychology.pdf

592 Glossary
phobic disorder A strong but apparently irrational fear, as
when one fears a mouse or fears to stand on a high
place when there is no danger of falling.
phoneme One of the basic sounds in a given language,
used in communicating meanings(s).
physiological cue A cue for space perception which is
due to the organism's biological makeup, such as retinal
disparity and accommodation of the lens.
pitch The qualitative aspect of sounds, which may be
described as high or low; determined chiefly by
frequency.
pituitary gland A structure at the lower end of the
hypothalamus which has extremely important endocrine
functions. Its anterior lobe secretes hormones which
play a role in sexual and general.body development. The
anterior lobe also secretes hormones which play a key
role in metabolic processes. Prolactin, important in
motivating maternal behavior in animals, is likewise
secreted by the anterior pituitary. The pituitary is
generally regarded as the master gland of the whole
endocrine system.
placebo (pluh-see'-b5) Literally, "to please." A pill of no
medicinal value given to a male patient, for example, "to
please him" or to make him think that he is taking
medicine. Used in drug experiments to prevent subjects
from knowing whether they have been given the drug or
a control substance and thereby distributing equally the
suggestive effects of taking the drug.
place theory The theory that the pitch of a sound is
determined by the place on the cochlea that is
maximally activated by a sound wave of a particular
frequency; loudness depends on the number of
activated fibers in each direction.
pleasure center An area of the brain, usually involving the
limbic system, which apparently produces a pleasant
reaction in an animal when stimulated electrically.
pleasure principle The tendency of organisms to seek
satisfaction of their urges.
pluralistic science A science composed of many different
elements; it cannot be accounted for by a single system
or approach, such as behaviorism, psychoanalysis, the
humanistic approach, or cognitive psychology. A field of
inquiry which is too diverse and amorphous to be
approached by just one method or theoretical
orientation.
point estimation Estimate of a point or value, such as a
population mean, on the basis of information from a
sample.
polarized fiber A nerve fiber in its resting state; a nerve
fiber not recently stimulated, which has opposite
charges on either side of its membrane.
pollution Impurity; the contamination of land, water, or
atmosphere through the presence of noxious
substances.
polygraph Apparatus for recording several responses
concurrently, such as a lie detector, in which changes in
respiration, blood pressure, and the GSR are recorded
simultaneously on a moving tape.
population All the objects, events, or subjects in a
particular class. For example, all the two-year-old babies
in the United States comprise a population, and some
babies from this group constitute a sample of the
population.
positive afterimage The brief continuation of a visual
experience, especially the sensation of color, after the
stimulus has been removed. Compare with negative
afterimage.
positive correlation A statistical concept indicating that
increases in one variable are associated with increases
in another variable; similarly decreases in the first
variable are associated with decreases in the second.
Among children of the same age, strength and exercise
show a positive correlation. The more a child exercises,
the greater is the child's strength.
positive transfer When learning one task facilitates the
learning of another.
pragmatics The study of the relationships between
language symbols and those who use them;
examination of language usage.
precipitating factor Any factor which appears to cause a
mental disorder; the most obviously disrupting event
prior to emotional maladjustment. If an individual
undergoes a divorce and shortly thereafter becomes
seriously maladjusted, the divorce is said to be the
precipitating factor. However, it is not necessarily, by
itself, the reason for the disorder. See predisposing
factors.
precognition The alleged extra sensory capacity of
knowing about future events without the aid of any of
the currently known sensory processes. See also
clairvoyance and telepathy.
predictive validity The extent to which a test is useful for
estimating future performance, particulary the capacity
to benefit from a training program and to perform
successfully at some future date.
predisposing factors Circumstances conducive to
maladjustment. If an individual has been physically ill
and loses his job, the chances of emotional
disturbances are increased. These conditions are called
predisposing factors for they predispose the individual
towards some other disturbance. See precipitating
factor.
prejudice Pre-judgment; an attitude or opinion formed prior
to or independent of an examination of the facts.
preoperational period The age from 18 months to
approximately six or seven years; during this period,
according to Piaget, the child's thinking tends to focus
upon the most striking feature of an object or event,
ignoring other aspects. The focus is upon states or
conditions, rather than transformations or operations,
hence the term preoperational thought.
pretest Early use of a test solely for the purposes of
evaluating that test, determining its strengths and
weaknesses, and identifying the items which need to be
eliminated or improved. Also, the use of a test to
establish the initial performance of a group of subjects,
before any program or treatment has been introduced.