Protocol - Motor and Attentional Impulsivity (Immediate and Delayed Memory Task)

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Immediate and Delayed Memory Task (IMT/DMT)




The Immediate and Delayed Memory Task (IMT/DMT) is a computer-based test where participants selectively and rapidly respond to a series of visual stimuli. The Immediate and Delayed Memory Task tracks both commission errors (motor impulsivity), which are responses to incorrect stimuli, and omission errors (attentional impulsivity), which are nonresponses to correct stimuli.

For more information about the Immediate Memory Task, please refer to its entry in the Cognitive Atlas http://www.cognitiveatlas.org/task/immediate_memory_task

For more information about the Delayed Memory Task, please refer to its entry in the Cognitive Atlas [http://www.cognitiveatlas.org/task/delayed_memory_task


Summary of the Immediate and Delayed Memory Task (IMT/DMT)

In the Immediate Memory Task, a series of randomly generated numbers (the default is 5-digit numbers (e.g., 38391)), appear on a computer monitor one at a time for 500 milliseconds (msec) each with a 500 msec delay between numbers. The participant is instructed to respond when two identical numbers are presented in sequence. The three main types of stimuli are target, filler, and catch stimuli. A target stimulus is a 5-digit number that is identical to the preceding number. Responses to target stimuli are recorded as correct detections. A catch stimulus is a number that differs from the preceding number by only one digit (position and value determined randomly). Responses to catch stimuli are recorded as commission errors. A filler stimulus is a random 5-digit number that appears whenever a target or catch trial is not scheduled to appear. Responses to filler stimuli are recorded as filler errors.

The Delayed Memory Task adds a series of distracter numbers ("12345" by default) between each stimulus to be compared to the previous in the series. Participants are instructed to ignore these distracter sequences, but the presentation of these sequences increases the length of time between two target stimuli and evokes a greater working-memory component to the task, similar to the N-back task.

The experimenter can set the software to collect either the IMT or the DMT or both (default), in a contiguous task session. The experimenter can also set the duration of the stimulus presentation and the intervals between stimuli, as well as the complexity of stimuli (number of digits) to yield optimal sensitivity for individual differences in different populations.


The IMT/DMT software generates a summary report for each session that includes: 1) rates of correct detections (and therefore rates of omission errors) 2) rates of commission error responses to catch stimuli, 3) rates of filler errors, 4) parametric and non-parametric indices or stimulus discriminability, and 5) parametric and non-parametric indices of response bias (i.e. liberal or conservative response behavior). A higher number of commission errors indicates an impulsive pattern of responding.

This program can be found at [link[www.nrlc-group.net/software/software.php|www.nrlc-group.net/software/software.php]]

Personnel and Training Required

The Immediate Memory Task can be administered by research assistants trained in the ethical and competent use of psychological tests.

Equipment Needs

The Immediate Memory Task can be installed on computers running Windows 2000/XP.


Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingNo

Mode of Administration


Life Stage:

Adolescent, Adult

Specific Instructions:

This Task is proprietary and can be obtained by submitting the software request form found on the "Development of Software" page of the Neurobehavioral Research Laboratory and Clinic website (University of Texas Health Science Center at San Antonio).

Research Domain Information

Release Date:

November 21, 2016


This measure requires and assesses sustained attention; it also assesses motor impulsivity as responding before complete evaluation of the stimuli.


Failure to inhibit commission errors to non-target stimuli is a component of impulsivity and is a risk factor for substance use disorders.

Selection Rationale

The Immediate and Delayed Memory Task is a widely used and validated, version of the continuous performance test for response inhibition, sustained attention, and working memory.




Common Data Elements (CDE)Neurobehavioral Impulsivity Questionnaire Assessment Score3371884CDE Browser

Process and Review

The [link[phenx.org/node/101|Expert Review Panel #3]] (ERP 3) reviewed the measures in Alcohol, Tobacco and Other Substances, and Substance Abuse and Addiction domains.

Guidance from ERP 3 includes:

• Changed name of Measure

• Updated protocol

• New Data Dictionary

Back-compatible: Partially back-compatible (updated/similar protocol which would require some changes to the data dictionary), variable mapping between current and previous protocols can be found [link[www.phenxtoolkit.org/index.php?pageLink=browse.archive.protocols&id=530000|here]].

Previous version in Toolkit archive ([link[www.phenxtoolkit.org/index.php?pageLink=resources.archive|link]])


This Task is proprietary. Investigators can obtain the Immediate Memory Task by submitting the software request form found on the "Development of Software" page of the Neurobehavioral Research Laboratory and Clinic website (University of Texas Health Science Center at San Antonio).

General References

Dougherty, D. M., Bjork, J. M., Harper, R. A., Mathias, C. W., Moeller, F. G., & Marsh, D. M. (2003). Validation of the Immediate and Delayed Memory Tasks in hospitalized adolescents with disruptive behavior disorders. Psychological Record, 53, 509-532.

Dougherty, D. M., & Marsh, D. M. (2003). Immediate and Delayed Memory Tasks (IMT/DMT 2.0): A research tool for studying attention, memory, and impulsive behavior. Houston, TX: Neurobehavioral Research Laboratory and Clinic, University of Texas Health Science Center at Houston.

Dougherty, D. M., Marsh, D. M., & Mathias, C. W. (2002). Immediate and Delayed Memory Tasks: A computerized behavioral measure of memory, attention, and impulsivity. Behavioral Research Methods: Instruments and Computers, 34, 391-398.

Liu, S., Lane, S.D., Schmitz, J.M., Waters, A.J., Cunningham, K.A., & Moeller, G.F. (2011). Relationship between attentional bias to cocaine-related stimuli and impulsivity in cocaine-dependent subjects. The American Journal of Drug and Alcohol Abuse, 37, 117-122.

Mathias, C. W., Marsh, D. M., & Dougherty, D. M. (2002). Reliability estimates for the Immediate and Delayed Memory Tasks. Perceptual and Motor Skills, 95, 559-569.

Dougherty, D.M., Lake, S.L., Mathias, C.W., Ryan, S.R., Bray, B.C., Charles, N.E., & Acheson, A. (2015). Behavioral Impulsivity and Risk-Taking Trajectories Across Early Adolescence in Youths With and Without Family Histories of Alcohol and Other Drug Use Disorders. Alcoholism, clinical and experimental research, 39(8), 1501-9.

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