Hard-Wired to See the Glass Half Empty?

RESEARCH

Is negative perceptual bias a trait of persons prone to major depressive disorder (MDD) or a modifiable symptom of the current depressive state? Noting that studies delving into this issue have returned contradictory results, a team of researchers from the Universitätsmedizin Berlin developed a tighter study design than those used in the past to clarify the nature of negative perceptual bias in individuals with depression.¹

The researchers explained that, if a negative perceptual bias can be shown to be a persistent, stable personality trait, it could prove useful in identifying persons at risk for MDD. If a negative perception bias is, instead, a symptom of the depressive episode, it could act as a marker for MDD and be useful in monitoring treatment response.

The research team conducted 2 experiments to examine emotion perception in 26 patients with MDD and 28 healthy controls matched for age, sex, and education level. The experiments were conducted at 2 time points-first when the patients with MDD were acutely depressed and again 3 months later. The first experiment assessed subjective biases in the recognition of facial emotional expressions. The second experiment assessed automatic emotion and attention bias using interocular suppression.

To improve upon emotion recognition testing and, thereby, enhance the sensitivity of their own results, the researchers used an array of facial images that were more nuanced/ambiguous and natural than those generally used in these types of tests. The images consisted of 4 sets (2 men and 2 women) of 11 facial expressions. Each set of 11 images morphed from very sad to neutral to very happy. Participants viewed the images, displayed on a computer screen, through a custom-made mirror stereoscope.

In the first experiment, a facial image was displayed for a second. After the participant logged-in a decision on whether the face was sad or happy, another face was displayed after a 2-second time lapse. Each of the 11 facial expressions was presented 16 times, for a total of 176 images rated by each participant.

[[{"type":"media","view_mode":"media_crop","fid":"39293","attributes":{"alt":"negative perception","class":"media-image","id":"media_crop_4205021228111","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4207","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"width: 199px; height: 176px;","title":" ","typeof":"foaf:Image"}}]]In the second experiment, participants were instructed to fixate on white-line squares placed in their field of view while high-contrast pattern masks were flashed to one eye. A facial image, faded into a quadrant of the view field, was displayed to the other eye. Participants were instructed to report, as quickly and accurately as possible, when they saw the face and where it appeared in the view field.

Through the first experiment, the researchers confirmed that MDD is associated with a negative perception bias. Compared with healthy controls, patients with acute-phase MDD needed to see a greater intensity of “happy” to identify a face as happy (P < .001). However, perceptual bias was affected by changes in depressive symptoms.

After 3 months, during which depressed patients received treatment, the negative perceptual bias was reduced and correlated with the reduction of depressive symptoms (P <.001). Findings from the second experiment failed to show that patients with MDD have a preferential access to awareness of sad versus happy faces.

The researchers ultimately concluded that negative perceptual bias in MDD is not a stable personality trait but a modifiable symptom reflective of the current patient’s current emotional state.

References:

1. Münkler P, Rothkirch M, Dalati Y, et al. Biased recognition of facial affect in patients with major depressive disorder reflects clinical state. PLoS One. 2015;10(6):e0129863. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0129863