In an online experiment, Benjamin Bellet, Payton Jones, and Richard McNally divided 270 Americans into two groups. Each group was assigned to read a series of passages from classic pieces of literature. All participants read ten passages, five of which contained no distressing material, and five of which contained severely distressing material (e.g., depictions of murder).
The two groups randomly created by the researchers were labelled the “trigger warning condition” and the “control condition”. In the trigger warning condition, each passage was preceded by the following statement: TRIGGER WARNING: The passage you are about to read contains disturbing content and may trigger an anxiety response, especially in those who have a history of trauma. No such warning was given in the control condition.
Emotional ratings about three “mildly distressing” passages were taken before and after the block of ten test passages. This let the researchers find out participants baseline levels of anxiety, and to establish whether the presentation of trigger warnings affected this baseline rating. Emotional ratings were also collected after each markedly distressing passage (a measure of immediate anxiety). In addition to this, participants also provided ratings in relation to their perceptions of emotional vulnerability following trauma (both in relation to their own vulnerability, and that of others), their belief that words can cause harm and that the world is controllable, and finally completed an implicit association test measuring their own sense of vulnerability/resilience.
After controlling for various factors, such as sex, race, age, psychiatric history, and political orientation, the researchers found that those participants who received trigger warnings were significantly more likely (compared to those in the control condition) to suggest that they and others would be more vulnerable to emotional distress after experiencing trauma (emphasis added).