Passage of Time or Delay Signal at the Level of Milliseconds: A New Approach and a Selective Difficulty in Individuals With Schizophrenia.

background and hypothesisIndividuals with schizophrenia report that time can feel discontinuous. Difficulties in benefiting from the passage of time at the level of hundreds of milliseconds are associated with the sense of self. However, time continuity might require millisecond-level processing. Here we leverage sequential effects in a synchrony judgment task to test whether individuals with schizophrenia and controls benefit from increased delays in the order of tens of milliseconds. STUDY

designWe re-analyzed 3 datasets (65 individuals with schizophrenia and 67 controls). Two visual stimuli appeared simultaneously or with a stimulus onset asynchrony (SOA, 8-96 ms). Rather than comparing sensitivity in asynchrony detection, we contrasted performance when the SOA increased, remained identical, or decreased from the previous to the current trial. In a control masking task, 19 individuals with schizophrenia and 19 controls located a masked target. STUDY

resultsPerformance improved for all participants when the SOA increased (and the task became easier), but more so for controls than for individuals with schizophrenia. These results were replicated across datasets and were specific to trials in which SOA increased on consecutive trials. This effect persisted even when SOAs were frequently identical and when we controlled for SOA magnitude. The group difference was specific to temporal judgments and was not observed in the masking task.

conclusionsThese findings reveal a difficulty for individuals with schizophrenia to benefit from delay signals at the millisecond level, which we suggest underlies their experience of time fragmentation.