CCTV Observation: The Effects of Event Type and Instructions on Fixation Behaviour in an Applied Change Blindness Task
Graham, G and Sauer, JD and Akehurst, L and Smith, J and Hillstrom, AP, CCTV Observation: The Effects of Event Type and Instructions on Fixation Behaviour in an Applied Change Blindness Task, Applied Cognitive Psychology, 32 pp. 4-13. ISSN 0888-4080 (2018) [Refereed Article]
Little is known about how observersíscanning strategies affect performance when monitoring events in closed-circuit
television (CCTV) footage. We examined the fixation behaviour of change detectors and non-detectors monitoring dynamic scenes.
One hundred forty-seven participants observed mock CCTV videos featuring either a mock crime or no crime. Participants were
instructed to look for a crime, to look for something unusual or simply to watch the video. In both videos, two of the people
depicted switched locations. Eye movements (the number of fixations on the targets and the average length of each fixation on
targets) were recorded prior to and during the critical change period. Change detection (24% overall) was unaffected by event
type or task instruction. Fixation behaviour differed significantly between the criminal and non-criminal event conditions. There
was no effect of instructions on fixation behaviour. Change detectors fixated for longer on the target directly before the change than
did non-detectors. Although fixation behaviour before change predicted change detection, fixation count and durations during the
critical change period did not. These results highlight the potential value of studying fixation behaviour for understanding change
blindness during complex, cognitively demanding tasks (e.g. CCTV surveillance).