The BIS is a 30-item scale that measures impulsivity personality traits initially developed over 50 years ago by Ernest Barratt. The current version – used in NSPN – is the BIS-11 developed in 1995. Some references are below:

• Stanford, M.S., Mathias, C.W., Dougherty, D.M., Lake, S.L., Anderson, N.E., & Patton, J.H. (2009). Fifty years of the Barratt Impulsiveness Scale: An update and review. Personality and Individual Differences, 47, 385-395.

Citation reference:

• Patton, J.H., Stanford, M.S., & Barratt, E.S. (1995). Factor structure of the Barratt Impulsiveness Scale. Journal of Clinical Psychology, 51, 768-774.

Participants were asked to think about how well each item describes how they act. Responses ranged from 'Rarely” to 'Always”. Only 13 of the questions had a response category which was endorsed less than 5% (majority of these items were between 3-4% of the sample). All four categories were in creating the subsequent scale. Items 1, 7, 8, 9, 10, 12, 13, 15, 20, 29, and 30 were reverse scored.

Initially principle components analysis of these 30 item revealed 6 first order subscales:

• Attention (items 5, 9, 11, 20, 28)
• Motor Impulsiveness (items 2, 3, 4, 17, 19, 22, 25)
• Self-control (items 1, 7, 8, 12, 13, 14)
• Cognitive Complexity (items 10, 15, 18, 27, 29)
• Perseverance (items 16, 21, 23, 30)
• Cognitive Instability (items 6, 24, 26)

These first order principle components were then submitted to a second order factor analysis and three second order factors were found: Attentional Impulsiveness (first order attention and cognitive instability), Motor Impulsiveness (first order motor and perseverance), and Non-Planning Impulsiveness (first order self-control and cognitive complexity). There is also a total score of all 30 items. The higher the score the more impulsive a person is meant to be and Stanford et al. (2009) suggest a cut-off of 72 could be used to classify an individual as highly impulsive.