Pain ratings reflect cognitive context: A range frequency model of pain perception Pat Watkinson a,⇑ , Alex M. Wood b , Donna M. Lloyd c , Gordon D.A. Brown d a School of Psychological Sciences, University of Manchester, UK b Behavioural Science Centre, Stirling Management School, University of Stirling, UK c Institute of Psychological Sciences, University of Leeds, UK d Department of Psychology, University of Warwick, Coventry, UK Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. article info Article history: Received 9 June 2012 Received in revised form 20 November 2012 Accepted 30 January 2013 Keywords: Context Judgment Pain Range Range frequency Rank abstract When painful stimuli are evaluated at the time they are experienced, judgments are made not in isolation but with reference to other experienced stimuli. We tested a specific quantitative model of how such con- text effects occur. Participants experienced 3 blocks of 11 different pressure pain stimuli, and rated each stimulus on a 0–10 scale of intensity. Stimulus distribution was varied between participants. Study 1 found that that the rating of a stimulus of a particular pressure was higher in the context in which it ranked highest. Study 2 found that pain ratings were higher in a context where most stimuli were rela- tively intense, even when the mean stimulus was constant. It is suggested that pain judgments are rel- ative, involve the same cognitive processes as are used in other psychophysical and socioemotional judgments, and are well described by range frequency theory. This approach can further inform the exist- ing body of research on context-dependent pain evaluation. Ó 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. 1. Introduction Self-reported pain is understood to involve cognitive evaluation as well as neurological response [7,10,24,25,33–35], and can be conceptualised as involving 3 stages: (1) neurological detection of the stimulus, (2) cognitive evaluation of the stimulus, followed by production of a response (a subjective opinion of how painful the stimulus feels), and (3) encoding of that particular experience in memory. Whilst much research focuses on neurological re- sponse [5,23,24,26,47] and pain memory [2,3,8,16,30,37,41,45] including tests of peak-end theory [14,15,31,36,40,42], there is much less research on (and currently no quantitative model of) judgments made at the time pain occurs. Some researchers assume that pain can be evaluated in isola- tion without reference to prior experience [2]; indeed, the assump- tion of context independence is implicit in the existence of pain rating scales [13,43,53], although use of these is now commonly believed to oversimplify the pain evaluation process [7,53]. Such an assumption would be consistent with an ‘‘absolute’’ account of pain judgment, according to which pain is predicted solely by the magnitude of the painful stimulus. Alternatively, as with other psychophysical judgments, real-time momentary pain judgments could be relative and depend on how a stimulus compares with other painful experiences. The basic understanding of self-reported pain depends on understanding how such relative judgments are made. We hypothesize that ratings of current pain can be influenced by other recent pain. How might such context effects occur? According to adaptation-level theory [11,18,33–35], pain might be evaluated relative to a perceived mean stimulus in the recent context. Alternatively, people might use the same judgment pro- cesses as they have been shown to use for other psychophysical stimuli. Such judgments are typically well described by range fre- quency theory (RFT) [27,28]. A demonstration that RFT character- izes pain judgments could link pain research with the study of other psychophysical [27,29,32] and socioemotional judgments [6,20,22,38,48–52,54–57]. RFT states that judgment of a stimulus depends on a combina- tion of its rank amongst other stimuli (the rank principle), and its position along the range of stimuli (the range principle). As applied to judgment of pain (a new domain for the application of RFT), the principles would operate as follows. Under the rank principle, the higher a stimulus ranks amongst other stimuli, the more painful it seems: F i ¼ðr i  1Þ=ðN  1Þ where F i is the judgment by rank of stimulus i, ranked at position r i in a context of N stimuli. 0304-3959/$36.00 Ó 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.pain.2013.01.016 ⇑ Corresponding author. Address: School of Psychological Sciences, University of Manchester, H22 Coupland Building 1, Oxford Road, Manchester M13 9PL, UK. E-mail address: pat.watkinson@manchester.ac.uk (P. Watkinson). PAIN Ò 154 (2013) 743–749 www.elsevier.com/locate/pain