The Making Of An Expert Detective 081116

The Making of an Expert DetectiveThinking and Deciding in Criminal InvestigationsIvar A. FahsingDepartment of PsychologyUNIVERSITY OF GOTHENBURGSweden 2016

There is nothing more deceptive than an obvious fact. – Sherlock Holmes Ivar A. FahsingPrint: Ineko, Sweden, 2016ISSN 1101-718X Avhandling/Göteborgs universitet, Psykologiska inst.ISRN GU/PSYK/AVH--347—SEISBN 978-91-628-9971-4 (print)ISBN 978-91-628-9972-1 (pdf)http://hdl.handle.net/2077/47515ii

DOCTORAL DISSERTATIONAbstractFahsing, I.A. (2016). The Making of an Expert Detective: Thinking and Deciding inCriminal Investigations. Department of Psychology, University of Gothenburg, Sweden.Drawing on theoretical frameworks developed in social and cognitive psychology, this thesisexamines the degree to which individual and systemic factors may compensate for inherent biasesin criminal detectives’ judgments and decision-making. Study I – an interview study – exploredcriminal detectives’ views of critical factors related to decision making in homicide investigations.Experienced homicide investigators in Norway (n 15) and the UK (n 20) were asked toidentify decisional ‘tipping point’– decisions that could change detectives’ mind-set from suspectidentification to suspect verification together with situational and individual factors relating tothese decisions. In a content analysis, two types of decision were identified as typical andpotentially critical tipping-points: (1) decisions to point-out, arrest, or charge a suspect, and (2)decisions concerning main strategies and lines of inquiry in the case. Moreover, 10 individualfactors (e.g. experience) and 14 situational factors (e.g. who is the victim) were reported as relatedto the likelihood of mind-set shifts, most of which correspond well with previous decisionmaking research. Study II, using a quasi-experimental design, compared the quality ofinvestigative decisions made by experienced detectives and novice police officers in two countrieswith markedly different models for the development of investigative expertise (England andNorway). In England, accredited homicide detectives vastly outperformed novice police officersin the number of adequate investigative hypotheses and actions reported. In Norway, however,bachelor educated police novices did marginally better than highly experienced homicidedetectives. Adopting a similar design and the same stimulus material, Study III asked if a generaltest of cognitive abilities used in the selection process at the Norwegian Police University Collegecould predict police students’ ability to generate investigative hypotheses. The findings did notsupport such a notion and this is somewhat in line with the available knowledge in the areashowing that cognitive ability tests have low predictability for applied reasoning tasks. Takentogether, this thesis suggests that investigative judgments are highly susceptible to the individualcharacteristics and biases of the detective. The results indicate that detective-expertise might actas a viable safeguard against biased decision-making, but length of experience alone does notpredict sound judgments or decisions in critical stages of criminal investigations. Education andtraining is a solid foundation for the making of an expert detective. Nevertheless all participants’researched across the two experiments were biased towards crime and guilt assumptivehypotheses. Hence, true abductive reasoning (i.e. to identify all competing explanations) and thepresumption of innocence is hard to operationalise even for expert detectives with extensivetraining.Keywords: Criminal investigation, Expert, Decision-Making, Abductive ReasoningIvar A. Fahsing, Department of Psychology, University of Gothenburg, Box 500, SE-40530, Gothenburg, Sweden. Phone: 47 92 22 55 33, E-mail: ivar.fahsing@phs.noISBN 978-91-628-9971-4ISSN 1101-718XiiiISRN GU/PSYK/AVH--347—SE

AcknowledgementsIt is common misconception that doing a PhD is an academic version of anightmare that never ends. Maybe I am an outlier, but doing this work hasbeen gratifying from day one and still is. The most gratifying part has beenall the inspiring discussions, idea exchanges, stimulating talks, andcollaborations that I have had the privilege to have with those people whohave supported and encouraged me in my pursuit as a researcher. I wouldlike to show my gratitude to all of you.A special gratitude goes to my supervisors, Karl Ask and Pär AndersGranhag. You accepted who I was and let me be who I am. You taught methe culture and language of proper science and research. A specialappreciation goes to my daily mentor Ivar Husby, your care, interest andadvice kept me on track when the road was slippery.Moreover, I want to express my gratefulness to Amina Memon, AndyGriffiths, Ann Harrison, Asbjørn Rachlew, Becky Milne, Camilla PelleginiMeling, Dave Walsh, Dag Sveaas, David Crompton, Finn Erik Rødsand,Grete Metlid, Hilde Sørum, Janne Stømner, Jon Roger Lund, Jon Stoddart,Jorunn Leksås, Karianne Moen, Laurence Alison, Marian Stenberg, MarkJackson, Nicky Miller, Nina Skarpenes, Nils Petter Michaelsen, Olof Wrede,Patrick Risan, Peter Jacobsson, Peter Stelfox, Petter Gottschalk, PålFrogner, Ray Bull, Simon Foy, Tony Cook, Thomas S. Roer, Tor TankeHolm, Trond Myklebust as well as the members of ACPO HomicideWorking Group, CLIP, The Norwegian Police University College, TheNorwegian Police Service and the rest of my friends around the world. Youdefinitely provided me with the motivation and inputs that I needed tochoose the right direction and successfully complete my thesis. Thank youall. Last, but not the least, a special thanks and gratitude goes to my belovedfamily. First and foremost, my dear Vivian, our beloved children Steffen,Tuva and Kristian, my sister Ingrid and my mother Hanne-Lise. Yourkindness, understanding, presence and love made it all possible. To all ofyou and to those I have forgotten – I am immensely grateful, touched,proud and once in a while a bit astonished.This work was supported by the Norwegian Police University College.iv

This thesis is based on the appended three papers, which are referred to bytheir roman numerals:I.II.III.Fahsing, I.A., & Ask, K. (2013). Decision making and decisionaltipping points in homicide investigations: An interview study ofBritish and Norwegian detectives. Journal of Investigative Psychology andOffender Profiling, 10(2), 155–165. doi: 10.1002/jip.1384Fahsing, I.A., & Ask, K. (2015). The making of an expert detective:The role of experience in English and Norwegian police officers’investigative decision making. Psychology, Crime & Law, 1–44. doi:10.1080/1068316X.2015.1077249Fahsing, I.A., & Ask, K. (2016). In search of the detective personality: Policerecruits’ logical reasoning and ability to generate investigative hypotheses.Manuscript submitted for publication.v

Svensk sammanfattning (Swedish summary):Syftet med föreliggande avhandling är att utifrån socialpsykologiska ochkognitiva teorier undersöka i vilken grad individuella faktorer hosbrottsutredaren och systemiska skillnader i utvecklandet av utredareskompetens påverkar vanliga bedömnings- och beslutsfel under utredningarav grov kriminalitet. Genom djupintervjuer undersökte Studie 1 vad erfarnabrottsutredare menar är de mest kritiska ”tipping points” i enmordutredning (dvs. beslut som gör att utredarens fokus skiftas frånundersökande till bekräftande), och vilka faktorer som kan påverka dessabedömningar. Brottsutredare från England (N 20) och Norge (N 15)med lång erfarenhet av brottsutredning beskrev hur beslut som fattas underkomplexa utredningar kan tänkas ändra utredarnas tankesätt frånundersökande till bekräftande, samt vilka individ- eller situationsfaktorersom kan påverka denna psykologiska process. Två karaktäristiska beslutnämndes av samtliga deltagare: (1) beslut kopplade till utpekning, anhållandeoch häktning av en misstänkt och (2) beslut angående vilka som är de mestcentrala hypoteserna och stegen i utredningsprocessen av ett fall. Tioindividuella (t.ex. utredningserfarenhet) och 14 situationsbundna (t.ex.tidspress) faktorer identifierades som samverkande med förändringar itankesätt. De flesta faktorerna korresponderade med tidigarebeslutsfattandeforskning. Studie II undersökte engelska och norska polisersförmågor att identifiera nödvändiga hypoteser och utredningssteg i enbrottsutredning, samt hur robusta förmågorna var mot en potentiell ”tippingpoint” som identifierats i Studie I (beslut om anhållande). Det finnsbetydliga skillnader i systemen för utveckling av kompetens mellan dennorska och engelska polisen. Därför jämfördes nyutbildade poliser ocherfarna mordutredare från de två länderna i en vinjettbaserad studie medutredningsärenden inspirerade av verkliga rättsfall. De erfarna engelskautredningsledarna presterade klart bättre än de övriga tre grupperna, medannyutbildade norska poliser med kandidatexamen presterade något bättre änerfarna norska mordutredare. Med utgångspunkt i forskningsdesignen ochmaterialet utvecklade för Studie II, undersökte Studie III i vilken gradprestationen på ett test av generell kognitiv förmåga som utförs i sambandmed antagningen på Polishögskolan i Norge kan predicera polisstudenternasförmåga att identifiera relevanta utredningshypoteser. Resultaten gav intestöd åt ett sådant samband, vilket delvis är i linje med den begränsadevi

tidigare forskningen i området. Sammantaget indikerar studierna att vissaindividuella skillnader mellan poliser i betydlig grad kan påverka derasbeslutsförmågor i centrala delar av en brottsutredning. Expertis ibrottsutredning kan utgöra en viktig skyddsfaktor mot fällor ibeslutsfattandet, men endast om expertisen utvecklas, dokumenteras ochtillämpas i ett system som inte uteslutande bygger på lång praktiskerfarenhet. Lång utredningserfarenhet kommer alltså inte i sig självt att görapoliser till experter, medan utbildning utgör ett fundament för utveckling avutredningsexpertis. Samtidigt visade alla deltagargrupper i Studie II och IIIen klar tendens att favorisera hypoteser som innebar att brott hade begåtts(jämfört med icke-kriminella hypoteser, som olycksfall, sjukdom, frivilligtavvikande, etc.). I linje med tidigare forskning på området visar alltsåavhandlingen på svårigheten att tänka abduktivt och därmed upprätthållaoskuldspresumtionen (dvs. ”oskyldig till bevisat skyldig”) – även förutredaremedlångerfarenhetochutbildningvii

Table of ContentsA MODERN-DAY WITCH-HUNT? . 1INTRODUCTION . 2CRIMINAL INVESTIGATION. 4Dirty Harry and Expedient Case Construction. 5Investigative Psychology and Environmental Constraints . 9Investigation as Sense-making and Abductive Logic . 12Investigation as Hypotheses testing . 15Models of Investigative Decision-making . 17BOUNDED RATIONALITY, HEURISTICS, AND COGNITIVE BIASES INCRIMINAL INVESTIGATIONS . 23Cognitive Bias. 24Satisficing . 24The anchoring and adjustment heuristic . . 24The availability heuristic . 25The feature positive effect . . 25The representativeness bias . . 26Framing effects . . 26Hindsight bias . . . 27Asymmetrical scepticism . 27Cognitive consistency theories . 27Order effects . 29Overconfidence. . 29Groupthink. .30Obedience . . 30Confirmation bias. 31Moderating Factors . 32Time-pressure . 32Motivation . 33Consequences of Heuristics an Biases in the Criminal Justice System . 34EXPERIENCE AND EXPERTISE . 36England and Norway: Different Paths to Detective Expertise . 40Is IQ a Predictor for Detective Expertise? . 46SUMMARY OF THE EMPIRICAL STUDIES . 51Study I. 52Study II . 53Study III . 57GENERAL DISCUSSION . 59Knowledge and Awareness . 60Expertise and Ability . 61Aptitude for Detection . 65Is the 'Effective Detective' a Myth? . 67Limitations . 70CONCLUDING REMARKS. 72References . 75