Conditional Expected Utility and the Acceptability of Deontic Health and Safety Rules Linden J. Ball & David Alford Department of Psychology LANCASTER UNIVERSITY Festschrift for David Over’s 60 th Birthday [Happy Birthday David!]

Indicative Conditionals vs. Deontic Conditionals INDICATIVE CONDITIONALS Factual claims Scientific knowledge Commonsense understanding ‘If you use vibrating power tools excessively then you will damage your health’ Hand-Arm Vibration (HAV) Vibration White Finger

Indicative Conditionals vs. Deontic Conditionals DEONTIC CONDITIONALS Social rules and laws Moral rules Organisational rules ‘If you have operated a vibrating power tool for 15 minutes then you must have a break’ HAV Syndromes: Number of people suffering from syndromes related to HAV: 288,000 in UK [UK Health & Safety Executive, 2004] Number of new claims for industrial disability benefit due to HAV exposure: 3,000 new cases each year in the UK [UK Health & Safety Executive, 2004]

Questions Addressed in the Present Research Why are some deontic rules seen as being ‘better’ rules than other deontic rules? What role does H&S content have in influencing people’s judgements about the ‘goodness’ of rules? What impact do financial penalties for rule violation have on people’s judgements of rule goodness?

What Does it Mean for an Indicative Rule to be Viewed as an Acceptable Rule? In interpreting an indicative conditional: The individual supposes the antecedent by hypothetically adding it to their stock of knowledge They then mentally simulate the consequent of the rule in the context of the antecedent (Ramsey test) How much the individual believes in the consequent under the antecedent – P(q|p) – determines the strength of the conditional (i.e., its ‘acceptability’) Over & Evans (2003); Oberauer & Wilhelm (2003) Suppositional Theory (e.g., Edgington, 1995; Evans & Over, 2004) ‘If you use vibrating power tools excessively then you will damage your health’

What Does it Mean for a Deontic Rule to be Accepted as a Good Rule? p&qThe VPT is operated for 15 minutes and the worker has a break p&¬qThe VPT is operated for 15 minutes and the worker does not have a break ¬p&qThe VPT is not operated for 15 minutes and the worker has a break ¬p&¬qThe VPT is not operated for 15 minutes and the worker does not have a break The Conditional Expected Utility (CEU) hypothesis (Over, Manktelow, & Hadjichristidis, 2004) ‘If you have operated a vibrating power tool for 15 minutes then you must have a break’ The acceptability of must rules depends on a person’s preference for the p&q possibility over the p&¬q possibility ‘If you have operated a vibrating power tool for 15 minutes then you may have a break’

Over et al.’s (2004) Evidence for the CEU Account Two experiments using prudential must and may conditionals showed that: Deontic conditionals were indeed judged as ‘good’ rules to the extent that the p&q possibility was preferred to the p&¬q possibility There was a systematic difference in the evaluation of must and may rules, with must rules being judged as ‘better’ The must/may difference generalised from self-imposed personal rules to rules expressed by an agent in a position of authority

Experiment 1: H&S Deontic Rules Aimed to examine CEU predictions for commonsense deontic rules with or without H&S contents 2 x 2 design: (1) Whether rules were obligations or permissions (2) Whether H&S content was present or absent Must + H&S Present (6 rules) If your are riding a motorbike then you must wear protective clothing May + H&S Present (6 rules) If you are wearing a bicycle helmet then you may ride your bike Must + H&S Absent (6 rules) If you meet up with your friends then you must have enough money May + H&S Absent (6 rules) If you extend your overdraft limit then you may buy some extra luxuries

Rule Goodness Evaluation Task If your are riding a motorbike then you must wear protective clothing How good a rule is this? Please respond by circling a number on the scale below a very bad rule neutral a very good rule

Situation Preference-Ranking Task Preference order: You are riding a motorbike and you wear protective clothing You are riding a motorbike and you don’t wear protective clothing You are not riding a motorbike and you wear protective clothing You are not riding a motorbike and you don’t wear protective clothing......

Detailed Objectives 1.Replicate must/may difference in rule ‘goodness’ judgements 2.Determine if must/may difference generalises to H&S rules 3.Examine if rules where H&S content is present are judged as ‘better’ than rules where H&S content is absent 4.Replicate must/may difference in preferences for p&q possibility over p&¬q possibility 5. Validate the CEU prediction that deontic conditionals will be judged as ‘good’ to the extent that the p&q possibility is preferred to the p&¬q possibility

Results: Mean Rule Goodness Evaluations Deontic Rule Form: F(1, 20) = 36.99, p <.001 H&S Content: F(1, 20) = 92.95, p <.001 Interaction: ns

Results: Mean Difference in Preference Ratings for the p&q Possibility over the p&¬q Possibility Difference Score calculated as: (p&¬q) – (p&q) (p&¬q) – (p&q) (motorbike & no protective clothing) – (motorbike & protective clothing) (4) – (1) +3 (p&¬q) – (p&q) (motorbike & no protective clothing) – (motorbike & protective clothing) (1) – (4) –3

Results: Mean Difference in Preference Ratings for the p&q Possibility over the p&¬q Possibility Difference Score calculated as: (p&¬q)-(p&q) Deontic Rule Form: F(1, 20) = 15.01, p <.001 H&S Content: F(1, 20) = 5.12, p <.05 Interaction: ns

Results: Comparing Rule Goodness Evaluations and (p&¬q)-(p&q) Difference Scores CEU Prediction: Deontic conditionals judged as ‘good’ to the extent that the p&q possibility is preferred to the p& ¬ q possibility To test this Spearman rank-order correlation coefficients were computed for each individual’s goodness ratings for a rule and their (p&¬q)-(p&q) preference ratings for the situations associated with the rule This produced 21 correlation values (one for each participant) 17 out of 21 values were in the predicted (+ve) direction

Experiment 2: H&S Deontic Rules + Financial Penalties for Rule Violation Aimed to examine CEU predictions for deontic rules with or without H&S contents 2 x 2 design: (1) Whether rules were obligations or permissions (2) Whether H&S content was present or absent Must + H&S Present (6 rules) If you are in a moving car then you must have your safety-belt fastened May + H&S Present (6 rules) If the headlights on your car are working then you may drive at night Must + H&S Absent (6 rules) If your library book has reached its return date then you must take it back to the library May+ H&S Absent (6 rules) If your television licence is valid then you may watch your television

Rule Goodness Evaluation Task If you are in a moving car then you must have your safety-belt fastened How good a rule is this? Please respond by circling a number on the scale below a very bad rule neutral a very good rule

Situation Preference-Ranking Task Preference order: You are in a moving car and you have your safety-belt fastened You are in a moving car and you don’t have your safety-belt fastened You are not in a moving car and you have your safety-belt fastened You are not in a moving car and you don’t have your safety-belt fastened......

Results: Mean Rule Goodness Evaluations Deontic Rule Form: F(1, 17) = 23.98, p <.001 H&S Content: F(1, 17) = 21.69, p <.001 Interaction: F(1, 17) = 5.46, p <.05

Results: Mean Difference in Preference Ratings for the p&q Possibility over the p&¬q Possibility Difference Score calculated as: (p&¬q)-(p&q) Deontic Rule Form: F(1, 17) = 47.90, p <.001 H&S Content: F(1, 17) = 4.95, p <.05 Interaction: ns

Results: Comparing Rule Goodness Evaluations and (p&¬q)-(p&q) Difference Scores CEU Prediction: Deontic conditionals judged as ‘good’ to the extent that the p&q possibility is preferred to the p& ¬ q possibility 18 correlation values (one for each participant) 17 out of 18 values were in the predicted (+ve) direction

Overall Conclusions Clear association exists between rule goodness evaluations and preference ratings for p&q situations over p& ¬ q situations (support for CEU theory and a decision-theoretic approach to the acceptability of deontic rules) Strong effect whereby people evaluate obligation (must) rules as more acceptable than permission (may) rules (cf. Over et al., 2004) Deontic rules containing H&S content are judged as more acceptable than those without H&S content Presence of financial penalties strengthens rule acceptability, but the pattern of predicted CEU effects remains similar across contents either with or without financial penalties

Future Directions (ProjectNemo) We now have a compelling paradigm for examining the acceptability of H&S rules in real-world work contexts We aim to examine possible influences on H&S rule acceptability (e.g., perspective effects, framing effects, temporal effects, and negation effects) If we can understand why deontic rules are seen as more or less acceptable in a physical work context then this can lead to ideas for strengthening H&S rules Possible role for technology-based ‘forcing functions’ as a means to encourage rule following (but difficult issues to tackle here concerning monitoring, trust and privacy)