Dot Probe Task

Background

The Dot-Probe Task (DPT) is a classic computerized cognitive-behavioral paradigm used to measure (implicit) attentional bias— the tendency of our attention to be automatically drawn toward (or away from) certain types of stimuli, such as threatening or emotional information.

The task was first developed by Colin MacLeod and colleagues to investigate attentional bias towards threats in people suffering from anxiety.

Dot Probe tasks combine a stimulus-pair presentation task with a simple categorization task of a probe that is presented in the location of one of the two presented stimuli. For example, MacLeod and colleagues presented pairs of words consisting of one threat word (e.g. DANGER) and one length-matched neutral word (e.g.LEAGUE) on top of each other in the middle of the screen for a short period of time. Once the word pair was erased, one of two probe stimuli (E or I) was presented in one of the word locations and participants had to categorize the probe as fast as possible by pressing the 'E' or the 'I' key on the keyboard. It is hypothesized that probes that are presented in the location of words that seize one's attention are detected and categorized faster than probes that replace attention-neutral information.

MacLeod and colleagues found that individuals suffering from anxiety were significantly faster categorizing probe stimuli that appeared in the vicinity of the threating words compared to those in the neutral word position, thus confirming that they selectively attended to threatening stimuli.

Variants of the DPT task such as the Attentional Bias Modification (ABM) procedure that manipulate the position of the probe to favor the positions of the non-threating stimuli have successfully been studied to re-train attentional biases and build new habits of attending to non-threatening information.

Task Procedure

The Millisecond implementation of the MacLeod Threat DPT procedure runs one practice block with 20 trials that simply uses digit word pairs (e.g. 'ten' vs. 'two') to familiarize participants with the DPT procedure. Once practice is completed, participants work on 96 threat-neutral word pairs that are matched in length. Each trial sequence starts out with the presentation of a fixation stimulus (+++) in the center of the screen for 500ms. The word pairs then appear with the words being presented above and below the fixation stimulus. The words disappear after an additional 500ms and a probe (E or I) appears in one of the word locations. Participants need to respond as quickly as possible by pressing the E key for E-probes and the I-key for I-probes. The probe stays on screen until a response is registered.

Half the trials present the threat stimuli on the top; half on the bottom. The location of the probe stimuli (in threat position vs. neutral position) as well as the type of probe (E vs. I) is likewise balanced.

What it Measures

DPT tasks measure implicit attentional biases

Psychological domains

• Implicit Cognition: Cognitive Processes not under conscious control
• Selective Attention: Focusing on a specific stimulus or task while filtering out distractions

Main Performance Metrics

• Threat Bias Index: Response Time Measure of Attentional Bias towards Threatening Information

Psychiatric Conditions

DPT measures have been successfully used to study the following patient groups (amongst others):

• Anxiety Disorders
• Major Depressive Disorder
• Substance Abuse
• Eating Disorders

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Dot Probe Task.

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Townshend J. M., Duka T. Attentional bias associated with alcohol cues: differences between heavy and occasional social drinkers. Psychopharmacology (Berl) 2001; 157: 67–74.

Field M.,Mogg K., Zetteler J., Bradley B. P. Attentional biases for alcohol cues in heavy and light social drinkers: the roles of initial orienting and maintained attention. Psychopharmacology (Berl) 2004; 73: 88–93.

Duka T., Townshend J. M. The priming effect of alcohol preload on attentional bias to alcohol-related stimuli. Psychopharmacology (Berl) 2004; 176: 353–62.

Field M., Duka T., Eastwood B., Child R., Santarcangelo M., Gayton M. Experimental manipulation of attentional biases in heavy drinkers: do the effects generalize? Psychopharmacology (Berl) 2007; 192: 593–608.

MacLeod, C. , Soong, L.Y., Rutherford, E., & Campbell, L.W. (2007). Internet-delivered assessment and manipulation of anxiety-linked attentional bias: Validation of a free-access attentional probe software package. Behavior Research Methods, 39, 533-538.

Melissa A. Miller, M.A. & Mark T. Fillmore, M.T (2010). The effect of image complexity on attentional bias towards alcohol-related images in adult drinkers. Addiction, 105, 883–890.

Lang, T. J., Blackwell, S. E., Harmer, C. J., Davison, P., & Holmes, E. A. (2011). Cognitive bias modification using mental imagery for depression: Developing a novel computerized intervention to change negative thinking styles.European Journal of Personality, 10, 855

Hakamata Y, Lissek S, Bar-Haim Y, Britton JC, Fox NA, Leibenluft E, Ernst M, Pine DS. (2012). Attention bias modification treatment: a meta-analysis toward the establishment of novel treatment for anxiety. Biological Psychiatry, 72, 429.