D ELAYS IN I NFORMATION P RESENTATION L EAD TO B RAIN S TATE S WITCHING , W HICH D EGRADES U SER P ERFORMANCE , AND T HERE M AY N OT B E M UCH W E C AN D O ABOUT I T

System delays are a major factor that harms user experience. Long delays often result in system abandonment, decreased user performance, and lost revenue for businesses. Although studies have provided important contributions on the consequences of delays, less is known about why system delays harm the user experience. Using fMRI, we examined how long system delays-compared to short delays- can change a user's brain state. Results showed that brain state switching was more likely during a long delay than during a short delay. Brain state switching was also more likely at the beginning of a task following a long delay than following a short delay. The default-mode network (brain regions associated with inattention) was more active during long delays than when users were engaged in the task. Furthermore, long delays were significantly related to worsened performance as measured in decision time in the task following a delay. This effect was mediated by brain state switching at the beginning of the task after the delay. We also attempted four different system design interventions to overcome this and found partial mitigation, but none eliminated the negative effect of delays.