4 October 2018
What is the value of objectively measuring emotional bias?
A negative, perceptual bias is associated with the onset and maintenance of mood disorders, and is therefore a therapeutic avenue of interest. Here we will discuss the launch of an objective assessment of emotional bias as a potential biomarker of mood.
What is emotional bias?
Bias in facial emotion perception typically refers to a tendency to view people’s emotions in a more negative or positive way.
Research suggests that people with mental health conditions, such as depression and anxiety (or other mood disorders) tend to view ambiguous emotions more negatively, e.g. more sad, indicating a negative bias in their processing of information (Bourke et al., 2010; MacLeod & Mathews, 2012). This 'negative bias' when perceiving the facial emotion of others has been proposed to contribute to the onset and maintenance of mental health conditions (Roiser et al., 2012).
Previous research has shown that drugs which modify such bias tend to have beneficial effects on mood disorders (Harmer et al., 2009; Roiser et al., 2012). Furthermore, the magnitude of change in bias predicts the extent of recovery (Warren, Pringle and Harmer, 2015). Together, these findings present emotional bias as a potential biomarker of mood and suggest it may have a range of potential clinical applications for improving patient identification and treatment (Cotter & Barnett, 2018).
How are mood disorders typically measured?
Subjective self-report is typically used to measure the symptomology and severity of mood disorders. By definition, self-report quantifies mood symptoms from the subjective introspection of the patient. Furthermore, self-report measures of mood typically require the patient to reflect on the frequency and severity of their symptoms over an extended time period i.e. the past two weeks.
These measures provide a useful insight into patients’ perspective of their condition, but there are two important considerations with their use:
- Subjective measures are unavoidably framed by the opinion of the reporter, in terms of both level of insight and willingness to share
- Memory degradation, which is a common symptom for many people with mood disorders, can make reflection over an extended period unreliable
These issues present a need to supplement current practices with objective measurements, which have the potential to disambiguate mood symptoms from their effects on patient reflection.
How can emotional bias be measured?
In order to address the need for objective measurement in mood disorders, researchers from the University of Bristol and Cambridge Cognition developed the Emotional Bias Task (EBT).
EBT was designed to objectively detect the presence and extent of bias in facial emotion perception. Crucially, EBT implicitly detects a person’s bias when perceiving the emotions of others; quantifying unconscious processing of the current situation.
What does the Emotional Bias Task entail?
Participants are asked to view a series of faces that have been morphed between two emotional expressions. Participants are tasked with deciding which of the two emotions each face displays, e.g. 'Happy' or 'Sad'.
The task only takes 4 minutes to complete and offers an easy-to-interpret, single outcome measure: the 'bias point'. The bias point is a digit between 1 and 15 which indicates the direction and extent of bias when perceiving facial emotions.
What are the key benefits of using the Emotional Bias Task?
EBT has been shown to be sensitive to the presence of bias when comparing a typically-developing control group to those with low mood (Penton-Voak et al., 2012). Furthermore, EBT’s bias point correlates with other common measures of depression (HAM-D, BDI-II) and mood, indicating it’s potential clinical utility (Penton-Voak et al. 2018).
Crucially, EBT circumvents many of the issues associated with subjective, self-report measures of emotional bias, being that it is:
- An objective measure (biomarker) of mood that measures an internal cognitive process (facial emotional perception)
- Sensitive to momentary fluctuations in mood
- Independent from memory quality and degradation
- Engaging for patients, requiring only short-bursts of their time and attention
- Does not require specialist training to administer or interpret
Interested in objectively measuring emotional bias?
Bourke, C., Douglas, K., & Porter, R. (2010). Processing of facial emotion expression in major depression: A review. Australian and New Zealand Journal of Psychiatry, 44, 681–696.
Cotter, J., & Barnett, J. H. (2018). Using Affective Cognition to Enhance Precision Psychiatry. Frontiers in Psychiatry, 9, 288. https://doi.org/10.3389/fpsyt.2018.00288
Harmer CJ, Duman RS, Cowen PJ. How do antidepressants work? New perspectives for refining future treatment approaches. Lancet Psychiatry 2017;4(5):409-18.
MacLeod, C., & Mathews, A. (2012). Cognitive bias modification approaches to anxiety. Annual Review of Clinical Psychology, 8, 189–217.
Penton-Voak, I. S., Bate, H., Lewis, G., & Munafò, M. R. (2012). Effects of emotion perception training on mood in undergraduate students: Randomised controlled trial. The British Journal of Psychiatry, 201(1), 71–72.
Penton-Voak IS, Adams S, Button KS, Fluharty M, Dalili M, Browning M, Holmes E, Harmer C, Munafo MR. Emotional recognition training modifies neural response to emotional faces but does not improve mood in healthy volunteers with high levels of depressive symptoms. bioRxiv (preprint) 2018;335042.
Roiser JP, Elliott R, Sahakian BJ. (2012). Cognitive mechanisms of treatment in depression. Neuropsychopharmacology, 37(1):117-36.
Warren MB, Pringle A, Harmer CJ. A neurocognitive model for understanding treatment action in depression. Philosophical Transactions of the Royal Society B, doi: 10.1098/rstb.2014.0213.