Verbal and pictorial single-item scales are as good as their 10-item counterparts for measuring perceived usability

Single-item scales of perceived usability are attractive due to their efficiency and non-verbal scales are attractive because they enable collecting data from individuals irrespective of their language proficiency. We tested experimentally whether single-item verbal and pictorial scales can compete with their 10-item counterparts at reflecting the difference in usability between well-designed and poorly designed systems. N = 1079 (Experiment 1) and N = 1092 (Experiment 2) participants worked with two systems whose usability was experimentally manipulated. Perceived usability was assessed using the 10-item System Usability Scale, the single-item Adjective Rating Scale, the 10-item Pictorial System Usability Scale and the Pictorial Single-Item Usability Scale. The single-item scales reflect the difference in usability as good as their 10-item counterparts. The pictorial scales are nearly as valid as their verbal counterparts. The single-item Adjective Rating Scale and the Pictorial Single-Item Usability Scale are thus efficient and valid alternatives to their 10-item counterparts. Verbal and pictorial single-item perceived-usability scales are viable alternatives to their 10-item counterparts. Specifically, the single-item Adjective Rating Scale is as good as the 10-item System Usability Scale and the Pictorial Single-Item Usability Scale is as good as the Pictorial System Usability Scale at reflecting differences in usability between systems.