Kneller W, Higham P, Hobbs M. Measuring manual dexterity and anxiety in divers using a novel task at 35–41 m. Aviat Space Environ Med 2012; 83:54–7. Background: Nitrogen narcosis has a detrimental impact on the manual dexterity of divers and prior research has suggested that this impairment may be magnified by anxiety. Preliminary findings of the effects of depth (i.e., narcosis) and subjective anxiety on a novel test of manual dexterity are presented. Methods: There were 45 subjects who were given a test of manual dexterity once in shallow water (1–10 m/3–33 ft) and once in deep water (35–41 m/115–135 ft). Subjective anxiety was concurrently measured in 33 subjects who were split into ‘non-anxious’ and ‘anxious’ groups for each depth condition. Results: Subjects took significantly longer (seconds) to complete the manual dexterity task in the deep (mean = 52.8; SD = 12.1) water compared to the shallow water (mean = 46.9; SD = 8.4). In addition, anxious subjects took significantly longer to complete the task in the deep water (mean = 48.6; SD = 6.8) compared to non-anxious subjects (mean = 53.2; SD = 9.9), but this was not the case in the shallow water. Discussion: This selective effect of anxiety in deep water was taken as evidence that anxiety may magnify narcotic impairments underwater. It was concluded that the test of manual dexterity was sensitive to the effects of depth and will be a useful tool in future research.