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Basic Task Description

Attention is a complex cognitive function, dependent on interacting neural systems of the brain. According to the Attention Network Theory, the systems can be subdivided into an alerting or vigilance network, a network of orientation or selection, and an executive or conflict network. A range of experimental, neuroimaging, and clinical studies have supported the theory and Berger and Posner as well as Fan et al. have argued that the attention network model is of special interest in studies of attentional disorders, e.g. the Attention Deficit Hyperactivity Disorder (ADHD).

The three networks have been widely explored by using cue-target reaction time (RT) tasks and tasks evoking a conflict. Recently, Fan, Posner and collaborators developed an experimental task called the Attention Network Task (ANT), combining a cue-target and a flanker test to obtain measures of the efficiency and accuracy of the three networks. Recent studies have used different versions of ANT to study cognitive characteristics associated with ADHD. A study by Booth used the original child version and found no differences between children with ADHD and control children on any of the three networks. An Event Related Potential (ERP) study by Rodriguez demonstrated a deviant ERP activation pattern on the alerting and conflict networks in young adults with the DSM-IV defined inattentive subtype of ADHD. A deviant activation pattern was also found in a Functional magnetic resonance imaging (fMRI) study by Konrad and colleagues. This affected all three networks, but the behavioral data showed that only the conflict network was less efficient in ADHD children than in control children. These results suggest that the neural basis of the attentional networks may be affected in children with ADHD, even when this is not reflected in behavior measures.

Task Procedure

This version of the ANT was programmed in E-Prime 2.0. Participant responses are made on computer keyboard, using the right and left arrow keys. At the beginning of the task, instructions are presented on the screen in yellow, size 20 Arial font, with a black screen background. The instructions are as follows:

Slide 1:

"In this experiment, you will see arrows pointing to the left or the right.

Your job is to press the LEFT key if the central arrow is pointing to the left, and press the RIGHT key if the central arrow is pointing to the right.

Sometimes the central arrow will be surrounded by other arrows pointing in the SAME direction: (example given) Sometimes the central arrow will be surrounded by other arrows pointing in the OPPOSITE direction: (example given) And sometimes the central arrow will be surrounded by lines that do NOT have arrowheads at all: (example given)

No matter what, just pay attention to the central arrow."

Slide 2:

"Place your hand on the table with your fingers extended and resting comfortably on the LEFT and RIGHT keys.

Press the LEFT key if the central arrow points to the left. Press the RIGHT key if the central arrow points to the right.

Please respond as quickly as possible. There will be a cross (+) in the center of the screen, and the arrows will appear either above or below the cross.

Try to keep your eyes on the cross throughout the experiment."

Each practice trial begins with a white fixation point on a black screen (randomized durations between 400-1200 ms), followed by a target stimulus consisting of five arrows. A total of 8 practice trials are administered, each of which consisted of a different combination of flanker congruency (congruent or incongruent), arrow direction (left or right), and spatial placement (above or below fixation). Feedback is displayed for 1000 ms following each practice trial. Correct trial feedback consisted of the word "Correct!" appearing in green ink in the center of the screen. Incorrect trial feedback consisted of the word "Incorrect" appearing in red ink in the center of the screen.

Following practice trials, participants are then shown another instruction slide that prepares them for the rest of the trials:


You have completed the practice. During the TEST you will not receive feedback.

Please ask the experimenter to start the TEST when you are ready"

Experimental trials follow general parameters similar to the practice trials, except that feedback is not given and neutral trials are included. Neutral trials consist of a central arrow surrounded by two sets of lines instead of arrows on each side. A total of 144 experimental trials are administered. Each of the 12 combinations of congruency, arrow direction, and spatial placement occur 12 different times.

Task Structure Detail

This is what we had worked on before, but could use updating. We'd like to capture a schema that can handle each of the tasks in the CNP, so please think general when editing -fws

  • Task Structure (please given an overview of the task procedures here [i.e., overall design, block, trial, and within-trial event structure and timing])
    • The ANT has two instructional screens at the outset, followed by practice trials and the experimental session.
      • Two instructional screens. Screens are advanced with a mouse click from the examiner.
        • 1. Basic task description.
        • 2. Explanation of response key mapping.
      • Practice trials (total of 8 trials).
        • Fixation Slide (randomized duration of 400-800 ms).
        • Target Stimulus Slide (1700 ms).
          • Feedback Slide (1000 ms).
      • Instruction screen instructs participants that feedback will no longer be given and introduces the experimental trials.
      • Experimental trials (144 trials).
        • Fixation Slide (randomized duration of 400-800 ms).
        • Target Stimulus Slide (1700 ms).
      • End. Thank you screen presented.
    • Timing
      • Instruction screens are static until advanced by examiner with a mouse click.
      • Fixation Slides (400-800 ms).
      • Target Stimulus Slides (1700 ms).
      • The ending thank you screen is static until advanced by the examiner with left mouse click.
  • Stimulus Characteristics
    • sensory modality: Visual. Fixation and arrows are white and appear on a black blackground. Instructions and feedback (practice) are yellow text in size 16 Arial font presented on a black background.
    • functional modality: visuoperceptual and linguistic (understanding of text).
    • presentation modality: computer display, directions are assisted by examiner.
  • Response Characteristics
    • responses required: Left or right arrow key press.
      • effector modality: Manual button press.
      • functional modality: Manual button press.
    • response options (e.g., yes/no, go/no-go, forced choice, multiple choice [specify n of options], free response): Forced choice.
    • response collection (e.g., examiner notes, keyboard, keypad, mouse, voice key, button press): Button press and recording of responses in Eprime 2.0.

Task Schematic

ANT Schematic 4a.JPG

ANT Schematic 4b.JPG


Stimuli consist of a central white fixation cross and five white arrows presented either above or below fixation. All stimuli are presented against a black background. Arrows were presented in one of three different manners, as shown in the task schematic. Congruent trials consist of a central arrow pointing either left or right with two arrows on each side facing the same direction. Incongruent trials consist of a central arrow pointing either left or right with two arrows on each side facing the opposite direction. Neutral trials consist of a central arrow pointing either left or right with two lines one each side.

Dependent Variables

The primary dependent variables associated with this task have been the differences in RT and accuracy between incongruent trials and congruent trials. Often termed a "conflict effect" or "executive control effect," these differences are calculated as a subtraction of incongruent RT (or accuracy) minus congruent RT (or accuracy). These are currently coded in the database as "ANT_CONFLICT_RT_EFFECT" and "ANT_CONFLICT_ACC_EFFECT". Specifically, ANT_CONFLICT_RT_EFFECT = ANT_MEAN_RTINC - ANT_MEANTRCON and ANT_CONFLICT_ACC_EFFECT = ANT_MEDIAN_ACCINC - ANT_MEDIAN_ACCCON. The former is most useful to index executive conflict. The latter is less useful in this sample because it is based on accuracy which is already at ceiling in both conditions, so in most cases ANT_CONFLICT_ACC_EFFECT = 0.

With regard to trial-by-trial congruency effects, primary dependent variables of interest include contrasts between the RT for each of the four types of congruency pair data involving congruent (C) and incongruent (I) trials. For example, "conflict adaptation effects" have been previously calculated as [iC - cC] + [cI - iI] (Kerns et al., 2005). These are currently not scored.

ANT Variables.jpg

Cleaning Rules

If any of the derived variables listed above are missing, participants should be flagged for exclusion. Additionally, participants who are outliers in the number of trial-by-trial congruency data should be flagged for follow up.

Performance is at ceiling in this task, but accuracy should be checked to exclude subjects performing below 50% accuracy in the congruent condition.


ANT Stone Scoring.jpg

History of Checking Scoring:

  • David Kaufman independently checked Stone's results in September 2010 and May 2011 and found his results to be accurate.
  • David Kaufman independently checked Stone's trial-by-trial congruency data in June 2011 and found it to contain errors.
  • EC added conflict effect DVs in July 2012.

History of Versions

Original Versions from Jin Fan:

Version 1.0

5/23/02 The SPACE key response is changed to 's' key response for the break slices since E-Prime version 1.0 is not compatible.

This the adult version for the measurement of three attentional networks --alerting, orienting, and executive control. Modify date: 7/12/00 By Jin Fan

Version 1.1 Use mouse buttons for the response. Also, the resolution of screen is changed from 640X480 to 1024X768. The distance from the screen to eye should be 53 cm. 8/1/00

Version 1.1B5 Updated the program to e-prime beta 5. Prerelease time was changed from 0 to 100ms.

Version 1.2 Updated the program to e-prime 2. Combined a left and right hand version into one, and added a dialog box at the beginning to find out which directions to give. 4/22/2008 by Marisa Geoghegan

CNP Version:

Version 1_1 (final for CNP; edited by Bob Bilder): This one has been revised for the CNP LA2K study. Some changes included here and NOT noted above include: 1. There was no need to have different versions, "HandUsed" is now a variable. 2. Experimenter advances all screens w/ mouse; S response is w/ left and right arrow keys. 3. Practice gives feedback in center of screen rather than above cross-hairs. 4. Real trials do not use the original Jin Fan method for adjusting trial duration. (basically, Jin wanted total trial duration at 3500ms to match scanner TR; instead, this version let's the initial fixation vary randomly from 400 to 800 ms; and the ITI is fixed at 400 ms; thus trial duration is variable. The task is about twice as fast and still includes uncertainty in when the stimulus will appear) 5. Lots of previously logged variables were eliminated, but most were in for no good reason. Maintained are all vars needed for scoring and timing audits.

Data Distributions




ANT Mean RT Inc-Con.JPG

ANT Mean RT Inc-Neu.JPG


ANT-SCWT Diff Score Corr.JPG


Fan J, McCandliss BD, Sommer T, Raz A, Posner MI. (2002). Testing the Efficiency and Independence of Attentional Networks. Journal of Cognitive Neuroscience, 14: 340-47.

Kerns JG, Cohen JD, MacDonald AW, Johnson MK, Stenger VA, Aizenstein H, Carter CS. (2005). Decreased conflict- and error-related activity in the anterior cingulate cortex in subjects with schizophrenia. American Journal of Psychiatry, 162:1833-39.