Risk perception and decision processes underlying informed consent to research participation

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Social Science & Medicine 65 (2007) 2105–2115

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Risk perception and decision processes underlying informedconsent to research participation

William W. Reynolds�, Robert M. Nelson

Department of Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Center for Research Integrity,

CHOP North Room 1511, 3405 Civic Center Boulevard, Philadelphia, PA 19104, USA

Available online 8 August 2007

Abstract

According to the rational choice model, informed consent should consist of a systematic, step-by-step evaluation of all

information pertinent to the treatment or research participation decision. Research shows that people frequently deviate

from this normative model, however, employing decision-making shortcuts, or heuristics. In this paper we report findings

from a qualitative study of 32 adolescents and (their) 31 parents who were recruited from two Northeastern US hospitals

and asked to consider the risks of and make hypothetical decisions about research participation. The purpose of this study

was to increase our understanding of how diabetic and at-risk adolescents (i.e., those who are obese and/or have a family

history of diabetes) and their parents perceive risks and make decisions about research participation. Using data collected

from adolescents and parents, we identify heuristic decision processes in which participant perceptions of risk magnitude,

which are formed quickly and intuitively and appear to be based on affective responses to information, are far more

prominent and central to the participation decision than are perceptions of probability. We discuss participants’ use of

decision-making heuristics in the context of recent research on affect and decision processes, and we consider the

implications of these findings for researchers.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: Risk perception; Decision making; Research ethics; Informed consent; Heuristics; Diabetes research; USA

Introduction

The underlying assumption of researchers whoassess informed consent for research participationappears to be that research subjects adhere to basicprinciples of rational choice. That is, they willunderstand required pieces of information about astudy, weigh their importance, and make the

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cscimed.2007.06.021

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s), [email protected] (R.M. Nelson).

decision that will optimize the expected value ofoutcomes (Lidz, 2006). However, there is evidencethat people frequently forego the systematic weight-ing and summing approach generally presumed byrational choice models such as Expected UtilityTheory (EU) for more intuitive decision-makingshort cuts, or heuristics. In addition, they may eitherunderestimate or overestimate the probability of therisks that are presented to them, depending on howthe information is framed (Kahneman & Tversky,1984; Lloyd, Hayes, Bell, & Naylor, 2001) or on anaffective response to the anticipated outcome(Rottenstreich & Hsee, 2001). Current approaches

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ARTICLE IN PRESSW.W. Reynolds, R.M. Nelson / Social Science & Medicine 65 (2007) 2105–21152106

to evaluating informed consent make little effort toaccount for heuristic- or affect-based decisionprocesses, ones in which patients ignore informa-tion, overweight certain elements, or base thedecision on factors not encompassed in the elementsof consent.

Most approaches to evaluating adult informedconsent or child assent assess recall of information(Mason & Allmark, 2000; Tait, Voepel-Lewis, &Malviya, 2003a, 2003b), which is different fromunderstanding. Recall is a function of the access onehas to the stored memory of an event, and it can beinfluenced by factors such as the salience ofinformation and the passage of time. Understandingof some components of informed consent may beequivalent to recall; however, this is not the casewith every consent component. For example, theprimary procedures one will undergo may berecalled easily. In contrast, understanding the risksof study participation is more complex as itnecessitates hypothetical thinking about potentiallyundesirable outcomes.

According to the Federal Regulations governingresearch participation, research risk is defined as‘‘the probability and magnitude of harm or dis-comfort anticipated in the research’’ (Departmentof Health and Human Services (DHHS) (1983) 45CFR 46.102(i); Food and Drug Administration(FDA) (2001) 21 CFR 50.3(k)). Risk magnitude iscommonly defined as an outcome’s severity, andprobability is the likelihood of the occurrence of anoutcome. While each of these components may becharacterized by a numeric estimate, this is notalways the case. Risk–benefit evaluations are madeup of a combination of qualitative descriptions andoften imprecise quantitative estimates, suggestingthat risk perception is a fundamentally subjectiveundertaking (Kopelman, 2004). An individual’sperception of risk may be difficult to evaluatesimply by asking people to recall the risks that arelisted on a consent document.

Do parents and adolescents examine all theavailable procedure information, weigh the risksand benefits, evaluate the probability and magni-tude of outcomes, and decide about researchparticipation based on this systematic process? Thisstudy aimed to: (1) generate knowledge about theeffects of risk perception on decision making aboutresearch participation and (2) explore how the priorexperiences of adolescents and parents affect theirperceptions of risk and decision making aboutresearch participation. We chose adolescent partici-

pants with Type I diabetes or who are at-risk forType II diabetes because similar participants hadbeen enrolled in prior studies that included medicalprocedures whose risk levels were in dispute. Inaddition, the presence or absence of an identifiedcondition plays a role in the acceptable level of riskan adolescent can be exposed to in research, so wewere interested in whether or not the ‘‘at-risk’’adolescents and parents perceived the presence of acondition.

To address the aims of this study, we chose aqualitative semi-structured interview methodologythat utilized hypothetical scenarios of medicalprocedures that were highly relevant to the presentmedical condition or family history of participatingadolescents. There are two main reasons a qualita-tive interview approach was considered mostappropriate for addressing the study aims. First,there is little empirical research on parent andadolescent risk perception and decision making inresearch participation, so an exploratory approachto the subject was warranted. Second, risk percep-tion is quite subjective, and several authors (e.g.,Kopelman, 2004; Slovic, 2000) emphasize theidiosyncratic nature of factors that affect percep-tions of risks (e.g., embarrassment, discomfort,inconvenience, stigmatization). In-depth interviewsfor this study provided participants the opportunityto talk about feelings and experiences that informtheir perceptions of risk without placing a priorilimitations, assumptions, or categories on theirresponses.

Methods

Sample

A sample of 32 adolescents and (their) 31 parentswas recruited for this study. Participants wererecruited from the endocrinology departments oftwo northeastern US hospitals and through referralsby other researchers who were aware of the studyinclusion criteria. In addition, a small numberresponded to recruitment fliers placed in andaround one hospital.

A purposive sampling strategy in which werecruited participants based on specific criteriarelated to their medical condition and researchparticipation experience was employed to yield arange of cases that would produce insights and in-depth understanding rather than empirical general-izations (Patton, 2002). Inclusion criteria were as

ARTICLE IN PRESSW.W. Reynolds, R.M. Nelson / Social Science & Medicine 65 (2007) 2105–2115 2107

follows: adolescents between the ages of 12 and 17who had diabetes or were at-risk for diabetes due toobesity (in the top 5% of the Body Mass Indexdistribution) and/or family history, and one of theirparents or guardians (see Table 1 for samplecharacteristics). These criteria reflected the charac-teristics of actual research participants in studiesthat involve glucose tolerance and insulin resistancetesting and provided variation of experience, in thatwe assumed the diabetic adolescents were likely tohave more familiarity with procedures to measureglucose tolerance and insulin resistance than theoverweight/at-risk group. Because there is someregulatory ambiguity as to what constitutes a‘‘condition,’’ which has implications for permissiblerisk exposure, we sampled for participants with anidentified disease (i.e., diabetes) and for those whowere healthy but who might be considered to have acondition due to a family history of diabetes and/orobesity. Based on their medical condition and/ortheir status of being at-risk for diabetes, allparticipants could be eligible for one or more of

Table 1

Sample characteristics

Adolescent (N ¼ 32)

Diabetes (N ¼ 15) Over

(N ¼

Gender

Male 10 (66.7%) 10 (5

Female 5 (33.3%) 7 (4

Race

Black/African-American 1 (6.7%) 10 (5

White 13 (86.6%) 6 (3

Other 1 (6.7%) 1 (5

Hispanic ethnicity

May be African American, white, or

other

1 (6.7%) 4 (2

Age

11–14 8 (53.3%) 14 (8

15–17 7 (46.7%) 3 (1

Parent education

Junior high school

Some high school

High school grad

Some college

Associate’s degree

Bachelor’s degree

Master’s degree

aOne parent of a boy from the overweight/at-risk group failed to app

more adolescent than parent in the sample.

the research procedures discussed in the hypothe-tical scenarios. At the time of their interviews fiveadolescents were participating in a research studythat utilized two of the procedures in the hypothe-tical scenarios. All participants received a 20-dollarstipend for their participation. This study wasapproved by the institutional review boards of bothparticipating institutions.

Data collection and analysis

The principal data in this study were verbatimtranscripts of individual interviews conducted with63 adolescents (32) and parents (31). The interviewswere structured around three scenarios describingmedical procedures that are used in endocrinologyresearch, an oral glucose tolerance test (OGTT), afrequently sampled IV glucose tolerance test(FSIVGTT), and a euglycemic insulin clamp proce-dure (Clamp) (see web-accessible Appendix A forprocedure descriptions and risk information). Par-ticipants read a procedure description and then

Parent (N ¼ 31)a

weight/at-risk

17)

Diabetes (N ¼ 15) Overweight/at-risk

(N ¼ 16)

8.8%) 2 (13.4%) 2 (12.5%)

1.2%) 13 (86.6%) 14 (87.5%)

8.8%) 1 (6.7%) 10 (62.5%)

5.3%) 14 (93.3%) 4 (31.3%)

.9%) – 2 (6.3%)

3.5%) – 4 (16%)

2.4%) N/A N/A

7.6%) N/A N/A

0 1 (6.3%)

0 1 (6.3%)

5 (33.3%) 3 (18.8%)

1 (6.7%) 6 (37.5%

3 (20%) 1 (6.3%)

5 (33.3%) 1 (6.3%)

1 (6.7%) 3 (18.8%)

ear for an interview appointment, which explains why there is one


asked a series of questions about their under-standing of the procedure, its risks, benefits, andany other observations. They then read informationabout the procedure risks and were prompted todiscuss their perceptions of these risks and theirdecision whether to undergo the procedure. Thisprocess was repeated for each of the three researchscenarios. Finally, participants were asked todiscuss risks they perceived in their everyday livesand to consider how these risks might compare tothe risks of research participation. The length of theinterviews ranged between 40 and 75min.

We constructed our scenario descriptions withlanguage taken directly from consent and assentdocuments used in studies employing one or moreof the three procedures (Arslanian, 2002; Caprio,2002; Goran, Coronges, Bergman, Cruz, & Gower,2003; Uwaifo et al., 2002). Two endocrinologyresearchers verified the credibility of our depictionsof the research procedures and risk information.

The interview guide was finalized after five pilotinterviews with diabetic adolescents and parentswere conducted. Upon completion of the first 10interviews, we created a thematic coding scheme totrack important ideas and sub-themes that werepresent. Both authors coded these and differenceswere discussed until agreement was reached oncodes. This coding structure became the generalframework for analysis of subsequent interviews;however, when additional themes not initiallypresent were identified, the authors discussed theirrelevance, created new codes, and applied thosecodes to previously coded interviews.

The qualitative analysis of these interview dataincluded repeated, close readings of transcripts todevelop preliminary codes which, as data accumu-lated, were adapted into a formal coding structure;memo writing; thematic coding aided by qualitativeanalytic software; conferencing between investiga-tors to ensure reliability of interpretation; andmatrix analyses for reducing and comparing aspectsof the data (Miles & Huberman, 1994). In addition,throughout the project we kept a journal in whichwe recorded analytic decisions, thoughts aboutdeveloping themes, and notes on overall progress.Comparisons between new incidents of a particulartheme and those that had been previously codedwere the core of the analysis and provided thefoundation for the eventual reduction and inter-pretation of interview text (Glaser, 1965). Datacollection ceased when we concluded that no newthemes were evident in the interviews.

Analysis of early interviews indicating that manyparticipants showed little concern with the risks ofthe hypothetical procedures raised questions abouthow actual participants in studies utilizing the samemedical procedures thought about risks. We thusbroadened our sample to include adolescents whohad recently made the decision to participate in aresearch study employing one or more of themedical procedures our prior participants haddiscussed hypothetically. Our inclusion of actualresearch participants was to improve the credibilityof our findings by adding cases that wouldpotentially confirm or disconfirm results fromrespondents who had never experienced thesemedical procedures.

Results

Participants in this study were adolescents withType I diabetes, adolescents at-risk for diabetes dueto being severely overweight and/or family history,and their parents. Results for all participants arepresented together because the majority of the non-diabetic participants responded as if their at-riskstatus was a condition. In addition, there were fewqualitative differences between the responses ofparticipants with or without research experience,and between parents and adolescents, so theresponses of the participants are not presentedseparately. Each interview was coded to identifycondition and order. In this coding scheme,A ¼ adolescent, P ¼ parent, H ¼ healthy (i.e., over-weight/at-risk group), and D ¼ diabetes. For ex-ample, PD01 is the parent of the first diabeticadolescent interviewed.

Participants discussed two components of therisks of the research procedures, the magnitude ofthe perceived risk, and its probability of occurrence.Statements of risk magnitude were more frequentthan mentions of probability (434 passages coded‘‘Magnitude,’’ 199 passages coded ‘‘Probability’’).These data suggest a process by which participantsinitially evaluated the magnitude of the procedurerisks and only then attended to probability (if atall). Multiple factors affected how magnitude wasused in risk assessment, but most participantsprocessed it in one of three ways: magnitude waseither acceptable, unacceptable, or it caused doubtsand needed additional consideration. If the severityof the risk outcome was acceptable, participantswere willing to tolerate the stated or perceived risksof the research procedure, regardless of probability.


Below are typical responses to acceptable risksbased on their severity from a mother and her 14-year-old son, who has diabetes:

[T]o me, this is a minor [risk] y he sticks himselfwith a needle all the time. As long as it’s clean y

the sugar high would just be a, a very temporarysituation y I don’t see those y two risks[infection, increase in blood sugar] as beingdetrimental to him (PD01, mother of a 14-year-old male)1.I think that they’re very minor risks [of OGTTprocedure], and I really don’t think there’snothing that could permanently damage you y

(AD01, 14 year old male).

For both these participants, the risk magnitudewas perceived to be ‘‘small’’ (or not ‘‘detrimental’’),that is, minor, and once this judgment was madethey did not request additional information to aid inthe risk assessment. Others made comments such as:

I know a lot of people that don’t like pain orgetting stuck or anything. But, to me, it’s not arisk. I’m used to it y (AD02, 17-year-oldfemale).[W]hen they’re talking about hypoglycemia, heexperiences that all the time, so it’s nothing thathe hasn’t dealt with before y I don’t seeanything else different here that would give meany great cause for alarm (PD06, mother of a 13-year-old male).

These comments demonstrated that one’s famil-iarity with the risk in question—being ‘‘used toit’’—was an important influence on perception ofthe severity of procedure risks.

What happened when the magnitude of a risk wasnot perceived to be as easily tolerated as in theabove examples? Nineteen of 63 (30%) participantswere unwilling to participate in one or moreresearch scenarios (two participants refused oneprocedure only, eight refused two only, and sevenrefused all three), due to the perceived severity ofthe risk information. AD11 showed the impact thatrisk severity could have on her thinking in responseto the risks of the FSIVGTT:

I could very well pass out depending on howmuch insulin was going into my body and howI’d react to the insulin is all up to how much mybody can handle. So passing out during this testis a big risk. Again, numbing, swelling, stuff likethat is a big risk, too, but passing out is an even

bigger risk y Having insulin delivered into myarm y if [my blood sugar] was low, then I wouldjust go lower, and that’s a really big risk, so Iprobably would not do this test (AD11, 15-year-old female).

She identified a number of factors that concernedher enough to reject participation in this procedure,regardless of probability, and her diabetes experi-ence clearly played a role in how she perceived therisks. Similarly, AH08 had experiences that madehim imagine a severe consequence to repeated IVsticks:

Well, my Pop Pop’s been in the hospital y andhe’s been stuck with needles so many times that Idon’t take any extra needles if I don’t have tobecause I don’t want my veins to collapse and fallover (AH08, 13-year-old male).

These two participants found the magnitude ofthe risks substantial enough to rule out participa-tion in one or more of the research scenarios.Although they and several others who had similarreactions did not need probability information tojustify their decisions, we explored whether a lowlikelihood of the risks would change their responseto the severity. In almost every case, the answer tothis question was emphatically ‘‘No.’’ For example:

(Interviewer: So even if they’re telling you, ‘‘They

[FSIVGTT risks] almost never happen. We’ve

never seen these things happen to anybody.’’) No, Istill wouldn’t do it because they’re still going tohappen. They’re just saying it ain’t neverhappened. It might be happening to me. It’s arisk (AH04, 14-year-old male).

Given the magnitude of the risks, any chance thatthey might occur is too great for him to change hismind about participation. A 12-year-old boy had asimilar response when told that complications fromtissue damage, one of the clamp procedure risks,almost never occur:

I would be worried, even if it is very rare y Itcould happen (AH13, 12-year-old male).

The perception that the risk could occur isenough to ensure that AH13 will not change hisdecision. These and other responses that refer tolikelihood show how probability information wasnot sufficient to overcome concerns about riskswhen the risk magnitude is perceived to be high.


When participants reacted negatively to themagnitude of the procedure risks but still hadreasons why they wanted to participate, fourparents and one adolescent explicitly requestedfrequencies or percentages of risk occurrence inorder to make their decision. The responses ofPD13, the mother of a 16-year-old girl, demon-strated how information about probability wasassessed when risk severity was a concern. Theperceived magnitude of the risks of the OGTT andFSIVGTT was tolerable, but when she heard therisk information for the Clamp procedure shereacted to the severity of the possible side effects:

[T]he infusion of sugar water may cause localtissue damage if it leaks outside the vein? I wouldbe curious as to y what kind of tissue damage,and what would that mean for her? I would justbe concerned of that.

The potential severity of tissue damage was aconcern for her, and she needed information aboutthe likelihood of occurrence to adequately assess therisk.

I guess if I felt assured that it was very a rarechance of happening y if they had done this teston multiple people and less than one out of ahundred people have had some kind of reaction,it would make me feel better.

After considering the likelihood of occurrence,she said:

[T]he higher the number—like less than one outof a thousand would be even better, and thehigher it goes, the better you feel y I would becurious as to how very rare y I would like toknow how did they get that, how they know it’sjust somewhat—what are the odds and y howmany people?

It is evident from these statements that when theacceptability of risks is uncertain, given one’ssubjective assessment of magnitude, the need forprobability information was activated. If partici-pants were still considering participation in ascenario when probability information was re-quested, they would generally agree to participatein the research. However, the risks that mostfrequently concerned participants were tissue da-mage and convulsions, and occurrence of each ofthese outcomes was highly unlikely under theconditions in which the procedures would beconducted.

In summary, in 52 of the 63 interviews themagnitude component of risk was more salient thanprobability in participants’ decision making. If themagnitude of outcomes was perceived to be small,there was no need for probability information.When magnitude of outcomes was a concern,attention to probability was rare and typically onlyevident when participants were uncertain about therisks of participation or other aspects of thedecision. PD09, the mother of a 16-year-old diabeticboy, expressed clearly this relationship betweenmagnitude and probability of risk.

A small blood clot that causes irritation is notvery serious y it’s the severity [that I’m mostconcerned with]. In this case, the severity of thepossible symptoms or risks are minor, even ifthey happen all the time. If you said to me thatit’s rare that it causes a heart attack, then I mightwant to ask for statistics.

In her evaluation of the risks of the researchprocedures, PD09 first considered how ‘‘serious’’she believed the risk to be. Once she determinedhow she viewed the severity, probability came intoplay, although in her case the risks were not seriousenough for her to need this information. The onlynoteworthy risk was the small blood clot, but shedecided that even were this to occur 100% of thetime, it was not severe enough to change her mindabout her son’s participation. Therefore, perceivedlow-risk magnitude made probability informationimmaterial to the decision.

Exceptions

Although these data support the idea thatparticipants’ risk perception is based more onperceptions of risk magnitude than on probability,every participant did not adhere precisely to thisapproach. In 11 cases, participants discussed risks ingeneral, using terms like ‘‘serious’’ or ‘‘minor’’without ever clearly identifying whether theirperceptions were in response to magnitude, prob-ability, or a combination of the two. Participantssometimes failed to respond to prompts asking themto clarify their thinking; at other times we may nothave recognized in the moment that a response wasambiguous. For example, AD13, a 16-year-old girl,responded to the OGTT risks:

They’re not like extreme risks. Some of them arerare, but I could see how people get nauseous y


I guess you would feel a little bit of pain, but itprobablyy it’s like a needle prick, so it wouldn’tbe that bad. I don’t see them as big risks.

Her first response referred to the risks in generalas not ‘‘extreme,’’ a comment which was followedimmediately by mention of their likelihood—somewere ‘‘rare.’’ Although she noted that the magnitudeof pain was small (‘‘little bit,’’ ‘‘not that bad’’),probability made an appearance before any explicitmention of risk severity. Her statement that therisks were not ‘‘extreme’’ may reflect her perceptionof magnitude, but it is not possible to state this withcertainty.

Other participants assessed probability and mag-nitude together rather than explicitly respondingfirst to the severity of the risks. For example, PH05called the risks of the OGTT ‘‘moderate,’’ withoutreferring to either probability or magnitude. Heclarified what he meant later, saying that the riskswere ‘‘really not too important,’’ which may be astatement of perceived magnitude, and then:

[I]t [OGTT risk information] really wouldn’thave a swaying effect on my decision, becauseymoderate to me is like a very limited chance of[having a problem] (father of a 14-year-old boy).

Thus, PH05 defined ‘‘moderate’’ in terms ofprobability rather than severity, but he was notconsistent in his focus on probability once the risksseemed more severe. When he heard the risks of theFSIVGTT, he said:

[F]our hours is a lot of time for him to be layingstill being part of a test. [H]e’s probably beinguncomfortable, and then insulin is a foreign bodysubstance that can have a reaction.Even though, the way it was explainedyit seemslike it’s minimal, but still, the word insulininjection is just spooky to me.

PH05’s response to the OGTT appeared to focusfirst on probability without overt reference to riskmagnitude. Upon review of his FSIVGTT com-ments, however, when risks are perceived as moresevere, an overall affective response (i.e., ‘‘spooky’’)dominated his perception. Once he had this reac-tion, he did not request probability information.

Overall, the vagueness of certain words these 11participants used to reflect risk perception limitedthe interpretability of their statements. Words andphrases like ‘‘extreme,’’ ‘‘not that bad,’’ and‘‘minimal’’ could apply to either probability or

magnitude (or both), so it is not clear that theseexceptions represented the prioritization of prob-ability over magnitude in the participation decision.

A note on perception of benefits

Results on risk perception explain why someparticipants refused the hypothetical studies. How-ever, for those who perceived little or no risks of theprocedures, there remains the question of why theywould decide to accept a time commitment andpotential pain or discomfort to participate in studiesnot directly beneficial to them. The commondefinition of ‘‘direct benefit’’ is a tangible positivehealth outcome, such as cure of disease, relief ofpain, or increased mobility that may be experiencedby an individual (Institute of Medicine, 2004).Although our scenarios were constructed to benon-beneficial in this sense, most who agreed toundergo one or more research procedures viewedtheir participation as having some personal valueindependent of a direct benefit, or perceived somebenefit that was valuable but not ‘‘direct.’’

It still seems like it’s okay because what they’redoing the research for is a good cause to helppeople y they was looking to help people out inthe long run, so I would consider, myself stilldoing a good deed (AH05, 14-year-old male).I don’t think it would have to benefit himdirectly. [W]e are the type of people that like tohelp people y so from our outlook, that wouldbe okay if it weren’t specifically helping [our son](PD06, mother of a 13-year-old male).I always go and do walks for the diabetescharities and everything else like that, and Ithink that this [participation] would just furtherhelp that cause. And that would feel good to meto help anyone in a similar situation (AD09,16–year-old male).

In addition, several participants, mostly from theoverweight/at-risk group, perceived informationthey would gain from participation to be a valuableoutcome of participation.

Discussion and implications

Our results support the presence of intuitive,heuristic decision making when participants wereasked to consider hypothetical research participa-tion decisions. Most participants quickly evaluatedthe procedural risks based on past experience with


similar medical tests or procedures and madedecisions accordingly. Some participants had animmediate negative affective response to the riskinformation based on an emotionally resonantpersonal experience that made it unlikely theywould participate. For most, however, the riskinformation was affectively neutral, and theydecided about participation based on their overallpositive feelings (e.g., that they might help others orthemselves in the future). Participants used theperceived magnitude of the risks to form theirimpressions, with the probability of an undesirableoutcome playing a small role.

Decision processes

Our results support the proposition that peopleuse what Slovic, Finucane, Peters, and MacGregor(2004) have called the affect heuristic to makejudgments and decisions. They argue that represen-tations of objects and events in people’s minds aretagged to varying degrees with affect, the specificquality of ‘‘goodness’’ or ‘‘badness’’ that (1) isexperienced as a feeling state (with or withoutconsciousness) and (2) demarcates a positive ornegative quality of a specific stimulus. Our partici-pants appeared to consult an ‘‘affect pool’’ contain-ing positive and negative tags associated with theirimpressions of the hypothetical research procedures.In addition, some of those with a past negativeexperience identified specific emotions such as fearor disgust that were triggered by the scenarios.Others had minimal reaction to the risks but a morefavorable affective response to the value of partici-pation. This finding supports the proposal thatnegative affective reactions may form the basis forjudgments of high risk and low benefit, andfavorable affective reactions may form the basisfor judgments of low risk and high benefit(Finucane, Alhakami, Slovic, & Johnson, 2000).Loewenstein, Weber, Hsee, and Welch (2001)suggest that intense and vivid emotions triggeredby a decision can override one’s analytical apprai-sal. Our finding that participants whose strongaffectively based negative decisions could not bealtered by attempts to encourage them to analyzeinformation about the low likelihood of riskyoutcomes is consistent with this suggestion. Usingan affective impression can be more efficient,especially when the required decision is complex(Slovic et al., 2004).

Affect-influenced decision making fits clearly intothe choice goals framework described by Bettman,Luce, and Payne (1998); see also Payne, Bettman,and Johnson (1993). This framework organizes thegoals for choice processing under several broad‘‘metagoals,’’ including maximizing the accuracy ofa decision, minimizing the cognitive effort requiredfor the decision, minimizing the experience ofnegative emotion while making the decision, andmaximizing the ease with which a decision can bejustified. With respect to affect, overreaction to riskis consistent with the finding that avoidance ofnegative emotion results in more lexicographictreatment of emotion laden decisions (i.e., thealternative with the best value on the mostthreatening attribute is selected). It is also consistentwith the finding that negative emotion results in agreater tendency to maintain the status quo. Forour participants who experienced negative emotionsin response to the risks of participation, the statusquo alternative was non-participation, even thoughthere was low probability of the feared outcomes.Choosing not to participate was also easy andcognitively efficient. Recently, Bettman, Luce, andPayne (2007) have proposed the additional meta-goal of seeking positive experiences in decisionmaking, which can help explain why other subjectschose participation when no direct benefits wereintended. Positive feelings of helping others andcontributing to science correspond to this goal.

Our participants formed their immediate impres-sions of the risks of the procedures based onperceived magnitude. If risks were perceived tohave low magnitude (i.e., little or no harm ordamage) probability information was irrelevant totheir risk assessment and usually not requested. In amore systematic, but similar, approach to ours,Huber and colleagues (Huber, Beutter, Montoya, &Huber, 2001; Huber & Macho, 2001; Huber, Wider,& Huber, 1997) used Active Information Search(AIS) methodology to explore decision making innaturalistic tasks. Rather than presenting subjectswith complete information, the AIS method pro-vides a minimal description of a decision and elicitsquestions from subjects about what additionalinformation they need to make a choice betweentwo options. Similar to our results, these authorsfound that choices could often be explained byutilities (or values) alone. If one outcome wasconsidered so negative that it was to be avoided,knowing probabilities would not change anything(Huber et al., 2001). They (1997) also found that in


the small number of cases where probabilityinformation was used, participants were satisfiedwith global information about uncertainty (i.e.,terms such as ‘‘unlikely,’’ and ‘‘not much chance’’were satisfactory), which was the case in our studyas well.

Brandstatter, Gigerenzer, and Hertwig (2006),working within the research program of Gigerenzer,Todd, and the ABC Research Group (1999),identified the priority heuristic, which makes explicitassumptions about the order of information acqui-sition for choices under risk. The priority heuristicconsists of a number of steps, including a priorityrule (i.e., an order for going through reasons), astopping rule, and a decision rule. The priorityheuristic predicted people’s preferences for differenttypes of gambles better than a number of previouslyproposed heuristics and several modificationsof EU theory (Brandstatter et al., 2006). Althoughnatural decision tasks, such as those used inour study, differ from gambles in a number ofaspects (Huber et al., 1997), our participants didprioritize outcomes first over probabilities, consis-tent with one of the main propositions of thepriority heuristic. We offer this only as a possibilitybecause the probability information presented toour subjects was global (e.g., terms such as ‘‘rare’’and ‘‘unlikely’’) in contrast to the specific propor-tions or frequencies given in most of the examplessupportive of the priority heuristic. As the proce-dures were non-beneficial, the utility of eachoption (i.e., participation or not) was inferredby the individual and therefore not consistentacross subjects.

Limitations

Our results are limited by the hypothetical natureof participants’ decisions. We cannot know whetherparticipants considered all factors that would berelevant to a real decision, nor whether theirdecisions in the hypothetical situations would reflecttheir actions in a real-world setting. There is someevidence that people make comparable decisions inhypothetical and real settings (Kuhberger, Schulte-Mecklenbeck, & Perner, 2002), but there have beenno previous studies in which hypothetical and realresearch participation decisions have been com-pared. We selected medical procedures that wereintended to resonate strongly with most of ourparticipants, perhaps creating a situation of ‘‘hotempathy’’ (Loewenstein et al., 2001). However, it is

unclear if this factor alone produced hypotheticaldecisions that would be the same as real ones.

Another limitation of these data is the lack ofvariability in participants’ perceptions of the risks ofthe research procedures. The great majority ofparticipants in this study was willing to participatein the research scenarios, and most perceived theoccurrence of higher magnitude risks (e.g., convul-sions, infection, tissue damage) to be unlikely. Inaddition, participants in the overweight/at-riskgroup responded as if they already had a condition.Hence, it is not clear if the process of decisionmaking described above would hold true for othermedical procedures of perceived higher risk or forparticipants who truly had no medical condition.

Implications

These data have important implications forinvestigators and others who are involved in theinformed consent process. Results suggest thatresearch participants interpret and use risk informa-tion subjectively, and they may overlook or findirrelevant information about risk probability.Hence, their interpretations of risk informationmay not match what researchers intend to commu-nicate. Research on risk perception of naturalhazards has shown that risk judgments may bereflective of behavioral experiences (Halpern-Felsher et al., 2001), and our findings likewiseindicate that perception of risk is greatly influencedby one’s personal experience. The same riskinformation can mean different things to differentparticipants and prompt different affective re-sponses depending upon one’s past experiences.This subjectivity of risk perception represents aproblem for investigators. How can they be certainthat consent is informed if risk information issubject to widely disparate, potentially biasedinterpretations?

Studies designed specifically to evaluate riskperception and communication have shown thatpatients can misunderstand or misinterpret riskinformation in a number of medical contexts(Eichmeyer et al., 2005; Gurmankin, Domchek,Stopfer, Fels, & Armstrong, 2005). However, thesestudies generally focus on the probability compo-nent of risk and draw few conclusions about howpatients’ affective reactions to perceived magnitudeof outcomes affect their decisions. It is unlikely thatphysicians typically evaluate their patients’ compre-hension and interpretation of risk information


during the process of informed consent for treat-ment or research (Michie, Lester, Pinto, & Marteau,2005), so the frequency with which misunderstand-ings happen is unknown. Although we made noformal evaluation of whether or not our partici-pants understood the procedure risks, our data, incombination with studies showing the subjectivityand variability of risk perception, suggest thatparticipants’ approach to risk and research decisionmaking may rely more on their affective responsesto a single or small number of key pieces ofinformation (e.g., severity of risks, value of partici-pation) than on the systematic weighting andsumming of all available information. Hence, theremay be a disconnection between the informationphysicians believe is important and communicateabout risk and how this information is interpretedand used by patients in their decisions.

Conclusion

Our data suggest that parents’ and adolescents’research risk perception and decision making forparticipation in hypothetical diabetes-related re-search procedures is influenced by subjective factorsthat may be difficult for researchers to identify in atypical consent conversation. The intent of in-formed consent is to protect patients by ensuringthat they understand important information aboutthe research study or treatment they will undergo.However, the affect heuristic and priority heuristic(as well as other lexicographic decision processes)enable decision making without requiring one toassess all available information. Probability infor-mation, especially, may be overlooked or deemed oflittle assistance in decision making, even though it istypically an element of consent that is givensubstantial weight by researchers and treatmentproviders. Researchers may find it difficult to assessthe extent to which their research participantsunderstand the risks of study participation whenthose participants employ affective and otherheuristic processes to evaluate risk information.

Acknowledgments

This research was supported in part by theGreenwall Foundation, institutional developmentfunds at The Children’s Hospital of Philadelphia,and by a Mentored Research Scientist DevelopmentAward to RM Nelson by the National Institute ofNeurological Disorders and Stroke. We would like

to thank the researchers who graciously shared theirinformed consent and assent forms with us, SilvaArslanian, Sonia Caprio, Michael Goran, BarbaraGower, and Jack Yanovski. We also thankresearchers and administrators at an outside institu-tion for permitting us to interview participants intheir studies. Finally, we thank the manuscriptreviewers, whose helpful comments improved thepaper considerably.

Appendix A. Supplementary materials

The online version of this article contains addi-tional supplementary data. Please visit doi:10.1016/j.socscimed.2007.06.021.

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Risk perception and decision processes underlying informed consent to research participation