Laboratory Behavioral Measures of Impulsivity

The Laboratory Behavioral Measures of Impulsivity (available from Donald M. Dougherty, PhD, at NRLC@wfubmc.edu) are a set of four computerized measures of behavioral impulsivity: the GoStop Impulsivity Paradigm, Two Choice Impulsivity Paradigm, Single Key Impulsivity Paradigm, and Time Paradigm. This set of tests allows researchers to integrate testing of distinct types of impulsivity within a single assessment battery. The tests are widely used in research settings, and they have excellent psychometric characteristics and validity across a variety of populations (e.g., children to adults) and conditions (e.g., medication).

The GoStop Impulsivity Paradigm measures the ability to inhibit responding. Individuals taking the test are instructed to click a mouse button at a “go” stimulus (consecutive matching 5-digit numbers that appear in black against a white computer background), and to withhold responding when they see a “stop” stimulus (consecutive numbers that change in color from black to red). Responses to numbers presented with the “stop” signal reflect a failure in the ability to inhibit responding.

The Two Choice Impulsivity Paradigm (TCIP) measures the ability to forgo immediate gratification for greater rewards at a later time. Individuals taking the test must choose between shapes appearing on a computer monitor. The choices result in either a small reward (points) delivered after a short delay (e.g., 5 seconds), or a larger reward after a long delay (e.g., 15 seconds). A tendency to select more of the smaller rewards is considered impulsive, because these choices result in less optimal consequences.

The Single Key Impulsivity Paradigm (SKIP) also measures the ability to forgo immediate gratification, but does not use the forced-choice procedure of the TCIP. Instead, in the SKIP, individuals taking the test are informed that they earn rewards (points) whenever they press a button, and that these rewards are earned in proportion to how long they wait between button presses. For instance, waiting 5 seconds between presses may earn 5 points, whereas waiting 15 seconds earns 15 points. The tendency to respond more frequently for smaller rewards is considered impulsive, because these choices result in less optimal consequences.

The Time Paradigm measures the perception of the passage of time. Individuals taking the test are instructed to estimate the passage of time by pressing a button to start and stop a timer, or to hold the button continuously during the estimation interval.[Page 526] A tendency to underestimate the passage of time is associated with impulsivity.