Effects of a Brief Mental Exercise on Emotional Processing

• Performance in an emotional categorisation task[ Time Frame: Completed at day 8 after exercise has been started ]
  Participants are presented with positive and negative personality descriptors and are asked to classify the valence of each word. These words describe either extremely agreeable/positive characteristics (e.g. "cheerful", "honest", "optimistic") or extremely disagreeable/negative characteristics (e.g. "domineering", "untidy", "hostile") and are presented individually in the centre of the screen. Participants are instructed to imagine themselves overhearing someone describing them with each of the words and to indicate as quickly and accurately as possible whether they would like or dislike to be described with each of the words. Responses are made by pressing a correspondingly labelled key on a button box. Reaction times for correct classifications are measured separately for positive and negative words.
• Performance in an emotional faces dot probe task[ Time Frame: Completed at day 8 after exercise has been started ]
  Pictures of positive and negative emotional stimuli (happy and fearful facial expressions) are presented individually together with a matched neutral stimulus (neutral face). On each trial, one stimulus is shown above and the other below a central fixation point. Subsequently, a probe appears behind one of the stimuli and participants have to correctly classify the probe as quickly and as accurately as possible. Stimuli can be masked (i.e. presented very briefly and followed by a jumbled face) or unmasked (i.e. presented for a longer period without a subsequent masking stimulus). Reaction times for correct responses are recorded and vigilance scores are calculated for masked and unmasked positive and negative stimuli by subtracting reaction time data from trials when the probe appeared in the same position as the emotional stimulus (congruent trials) from trials when the probe appeared in the opposite position to the emotional stimulus (incongruent trials).
• Performance in an emotional recall task[ Time Frame: Completed at day 8 after exercise has been started ]
  Following a delay period after the emotional categorisation task (about 15 min), emotional recall memory is assessed. Participants are asked to recall and write down as many words as possible from the emotional categorization task. Numbers of correctly and incorrectly recalled positive and negative words are measured.
• Performance in an emotional recognition task[ Time Frame: Completed at day 8 after exercise has been started ]
  Following the emotional recall task, emotional recognition memory is assessed by presenting participants with the original personality descriptors plus an equal number of matched distractor words (50% positive, 50% negative). Participants are asked to indicate for each word as accurately and as quickly as possible whether they recognise it from the emotional categorization task. Numbers of correctly and incorrectly recognised items as well as reaction times for correct recognitions are measured separately for positive and negative words.
• Change in cortisol awakening response[ Time Frame: Completed at day 8 after exercise has been started ]
  Salivary cortisol is assessed prior to and after completion of the 7-day exercise period. For each assessment, participants have to provide five saliva samples taken in their own home (0, 15, 30, 45, and 60 minutes after awakening).

The aim of this study is to explore whether a brief mental exercise (developed and widely advocated in the field of positive psychology) can change the processing of emotion-related information in a similar way as previously observed for antidepressant drugs. Healthy volunteers are randomly allocated to a 7-day practice of the "Three Good Things" (TGT) exercise or a previously used placebo exercise (unspecified childhood memory recall) with study participants as well as investigators being blind as to which practice is conducted. After a 7-day practice period, all study participants undergo testing with the Oxford Emotional Test Battery, an established battery of cognitive tasks that allow to assess how emotional information is processed. We hypothesise that the TGT exercise, as compared to the placebo exercise, can push the processing of emotional information towards a prioritisation of positive (relative to negative) input.

• Behavioral: Three good things exercise
  Participants are asked to remember each evening three things that went well during their day and to write them down in a journal including a short explanation of why they think each of them has happened.
• Behavioral: Placebo exercise
  Participants are asked to briefly recall a childhood memory (no further specification) and to write it down including a short explanation why they think it has happened.

• Experimental: Three good things exercise
• Placebo Comparator: Unspecific childhood memory recall exercise