### T-Score

A standard score that sets the mean to fifty and standard deviation to ten. Used on a number of tests including the MMPI.

### t-Test

A group of statistics used to determine if a significance difference exists between the means of two sets of data.

### Tactile

The sense of touch.

### TAT

See Thematic Apperception Test

### Temperament

A personâ€™s typical way of responding to his or her environment.

### Temporal Lobe

One of the four lobes of the brain. Contains the auditory cortex and therefore plays a role in receptive language as well as memory and emotion.

### Test-Retest Reliability

The correlation coefficient determined by comparing the scores of the same measuring device administered to the same people on two different occasions.

### Tetrachoric Correlation

A correlational technique used to estimate the Pearson-Product correlation of two continuous variables that have been dichotomized (Example: age is continuous, but when it is split into two groups, such as over 40 and under 40, it becomes dichotomous).

### Thalamus

Considered the central switching station of the brain because all of the body’s senses (except the olfactory senses) pass through this before being relayed to the brain.

### Thematic Apperception Test (TAT)

A subjective personality test where ambiguous pictures are shown to a subject and they are asked to tell a story related to them.

### Theory

A general idea about the relationship of two or more variables.

### Time Series Design

A research design where subjects are measured at specific times before and after the treatment has been administered in order to determine the long term effects of the treatment

### Trait

A relatively permanent internal characteristic (e.g., friendly, outgoing)

### Transference

Intense feelings directed toward the therapist that many clients experience in the process of therapy.

### Trial and Error Learning

Learning that takes place through the application of possible solutions to a problem.

### True Experiment

Research design that utilizes the most control over subjects and utilizes randomization

### True Score

the amount of the observed score that truly represents what you are intending to measure.

### Two-Way ANOVA

An Analysis of Variance used when there are two independent variables.

### Type A Personality

A theory used to describe a person with a significant number of traits focused on urgency, impatience, success, and excessive competition.

### Type B Personality

A theory used to describe person with a significant number of traits focused on relaxation, lack of urgency, and normal or reduced competition.

### Type I Error

The error that is committed when a true null hypothesis is rejected erroneously. The probability of a Type I Error is abbreviated with the lowercase Greek letter alpha.

### Type II Error

The error that is committed when a false null hypothesis is accepted erroneously. The probability of a Type II Error is abbreviated with the uppercase Greek letter beta.