Affective Attentional Bias Training In Depression
Affective Attentional Bias Training In Depression
Biased attention toward negatively valenced information has been considered as a mechanism
 for risk and relapse in depression. Those with depression tend to focus their visual
 attention first, more frequently, and for longer periods of time, if it connotes negative
 (particularly sad) mood. To this end, investigators have recently discovered that this bias
 might be modifiable. However, the existing literature is mixed with regard to effectiveness.
 The investigators propose in this study a novel approach to modifying attention bias in
 depression by using real time feedback with eye tracking technology. The investigators will
 examine if, compared to a sham condition, rewarding attention toward positive stimuli results
 in improved mood and reductions in attention bias. Following three sessions of either sham
 training or active attentional bias training, the investigators hypothesize that participants
 in the active training condition will experience a) reductions in negative attentional bias,
 and b) to an improved mood state and increased quality of life, compared to those in the sham
 training condition.
The existence of a negative affective bias in depression has been consistently supported
 throughout literature and has been identified as one of many factors that are associated with
 depressive symptomatology. A negative affective bias in depression refers to the fact that
 individuals with depression or depressive symptoms are more likely to focus on negative
 stimuli and less likely to pay attention to positive stimuli. Typically, this bias is most
 prominent and consistent in relation to sad stimuli, as opposed to other negatively valenced
 stimuli, such as anger or fear. Affective bias has been found to play a role in both the
 onset and maintenance of depressive disorders, and extends to information interpretation,
 memory, and attention.

 Such findings regarding the influence of this negative affective bias on depressive symptoms
 has spurred further research that aims to reduce or 'correct' this bias in an attempt to
 improve mood state and reduce depressive symptoms. This research has generally focused on the
 use of dot-probe attention bias modification (ABM) paradigms, which are forms of cognitive
 bias modification that attempt to 'train' attention towards positive stimuli and away from
 negative stimuli through a manipulation of the dot-probe. ABM paradigms have found success in
 a number of studies, and have been shown to be effective in decreasing the attentional bias
 for negative information, increasing attention for positive stimuli, and decreasing
 depressive symptoms leading to improvements in mood. Thus, ABM research represents a
 promising avenue for treating depressive symptoms through the elimination of the negative
 affective bias.

 However, the diverse methodology, stimuli, and design of existing research has led to
 conflicting and inconsistent results, with some studies being either unable to manipulate
 attention at all or failing to significantly improve mood. The use of the dot-probe paradigm
 as a means of modifying or training behaviour has been contested, with some findings
 suggesting that it is unable to induce either a positive or a negative attention bias.
 Moreover, single-session dot-probe paradigms in particular often fail to achieve any
 significant effects, which may be a result of insufficient durations to produce a change in
 attention. Additionally, designs that use negatively valenced emotions other than sadness may
 be weakened due to the fact that an attentional bias towards negative emotions other than
 sadness in depression has not been consistently demonstrated. Finally, it is common for
 similar studies to make use of either dysphoric populations or undergraduate populations with
 varying degrees of non-clinical depressive symptoms. Oftentimes, such studies fail to produce
 robust effects, which may be a result of an affective bias being less pronounced in
 non-clinical populations, or a result of a floor effect, in which less-depressed participants
 with lower initial depressive scores do not experience statistically significant changes. It
 would be premature to dismiss the effectiveness of attention modification training for
 affective biases in depression without addressing, clarifying, and improving upon such
 potential weaknesses in design and implementation.

 The proposed novel attention bias modification study seeks to administer a novel training
 paradigm that utilizes a reward-based, naturalistic, free-viewing design. It is expected that
 the design of this study will improve upon past research in four ways: 1) by overcoming the
 limits of the dot-probe through a free-viewing paradigm; 2) by utilizing only stimuli that
 represent 'sadness' and no other negatively valenced stimuli; 3) by providing multiple
 training sessions to induce a meaningful effect on attention; and 4) by providing treatment
 to individuals with MDD who might be more likely to benefit from ABM for a negative affective
 bias.

 This study will take place over five sessions over approximately two weeks: a pre-training
 assessment, three sessions of affective bias or sham training, and a post-training
 assessment. Participants will be asked to complete a brief, at-home measure of mood state on
 each day between pre- and post-assessments. Participants will be told that the study involves
 attention and learning, but to preserve blinding, they will only be told that the study is
 specifically an "attention training" study.

 Upon arriving in the lab for the pre-treatment session, participants will be asked to read
 letter of information regarding the study. Once they have read the letter and their informed
 consent is provided, a trained researcher will collect demographic information and then
 provide the participant with the BDI, Rumination Scale, and Sheehan Disablity Scale forms to
 complete privately. Following completion of the forms, participants will be led into a
 separate room containing the eye-tracker to complete a baseline assessment of affective bias
 and cognition.

 Cognitive assessment: Participants will complete the Emotional Verbal Learning Test . The
 EVLT is a measure of emotional learning and memory. It involves the oral presentation of
 emotional words by an experimenter to a participant. Participants will then engage in a
 short-delay (immediate) and long-delay (after 20 minutes) free recall of the words.
 Participants will then complete digit span and digit symbol coding tasks, which are widely
 used measures of attention and will take approximately 7 minutes to complete.

 Affective bias assessment: First, affective bias will be assessed using a free-viewing
 eye-tracking paradigm that is similar in design to the subsequent training sessions. During
 each trial, a black fixation cross will appear in the centre of the white screen for 500ms.
 Four unique faces in a drawn from the NimStim Set of Facial Expressions will then appear in a
 2x2 grid in the four quadrants of the screen, depicting one positive (happy) face and three
 negative (sad) faces. The location of the happy face will be randomized to any of the four
 quadrants over each trial. Participants will be told to freely view the faces and data will
 be collected via the eye-tracker on variables such as location of first fixation, total
 fixation duration on each type of valenced image, and total number of fixations on each type
 of image. Each set of faces will remain on the screen for a total of 3500ms before a new
 trial will begin. There will be a total of 120 trials, separated into two blocks of 60 trials
 with a 30-second break between blocks.

 Second, the parallel line task will be used as a measure of affective bias towards sad
 stimuli. In this task, 32 sad stimuli and 32 neutral stimuli will be presented. On either
 side of the picture, short grey lines will be presented, and each line will be tilted
 slightly to the left or right. In half of the trials, the lines will be tilted in the same
 direction (parallel), and in the remaining trials the lines will be tilted in opposing
 directions. Subjects will be asked either to indicate whether the type of picture being shown
 is sad or neutral (and thus ignore the lines), or to indicate whether the lines are parallel
 or different (and thus ignore the picture content). The reaction times to each type of
 display will be analyzed. Participants will complete 256 different trials for a total task
 time of about 22 minutes.

 Training Sessions: Affective attentional training will be completed by participants in-lab
 using an eye-tracker in three different sessions over the course of approximately one week.
 The attention training paradigm to be used was developed for the present study. The modified
 ABM task was developed to train participants' attention away from negative stimuli and
 towards positive stimuli through punishment and reward, respectively.

 The active training task will include one positively and three negatively valenced faces
 (showing either happiness or sadness, respectively), selected from the NimStim Set of Facial
 Expressions, will be presented in a random orientation in a 2x2 grid on the screen.
 Participants will be instructed to view the images naturally. All four faces will originally
 appear slightly blurred. Participants will be told that the purpose of the training is to
 enhance their ability to focus on images that become clearer while avoiding those that become
 blurrier.

 Each trial in the active training group will begin with a black fixation cross in the centre
 of a white background. The cross will appear alone for 500ms. After the 500ms, the four
 valenced faces will appear, with one in each quadrant of the screen, equally spaced from the
 central fixation cross, and participants will begin freely viewing the stimuli. If
 participants fixate on any of the three negative faces for more than 300ms, the face will
 undergo a processing of blurring for 500ms or until the participant looks away. This is meant
 to "punish" the participant by removing the social stimuli, and influence them to adjust
 their focus to more rewarding stimuli. If the participant fixates on the positive face for
 300ms, then this image become clearer over a span of 500 to 1500 ms or until the participant
 looks away. This is meant to "reward" participants for focusing on positive stimuli. If
 participants maintain their attention on the positive face until it becomes fully clear, the
 trial will be successful and the images will disappear, and the program will move on to the
 next trial. If a positive fixation does not occur within 4500ms, the trial will automatically
 end and the next trial will begin.

 In the sham training group, the paradigm will function exactly the same as the active
 training group, except that the stimuli will be neutral, non-affective, non-social photos
 (i.e., cars), with a photo type (i.e., forward facing car) being chosen as the "rewarding"
 stimulus and the remaining three photos acting as "punishing" stimuli.

 Training will be delivered through five five-minute blocks separate by 90-second rest
 periods. Participants will complete as many trials as they are able within each five-minute
 block. Each training session should take approximately 35 minutes, for a total of 105 minutes
 of attention training throughout the course of the week long training.

 Post-assessment: The post-assessment will be conducted in-lab during the week following the
 training sessions. It will consist of a re-administration of the same procedures at baseline.
Inclusion Criteria:

 -  Diagnosis of Major Depressive Disorder (MDD)

 -  Normal or corrected-to-normal vision

 Exclusion Criteria:

 -