Health care professionals learn that some diseases may be associated with various population groups. Doctors and nurses, for example, need to know if some categories of people are more likely than others to manifest specific symptoms and diseases. Ashkenazi Jews have a higher prevalence of Tay-Sachs disease than other groups. Hypertension is more prevalent among African Americans and Native Americans than White Americans. Such facts are essential to medical training and depict an accurate stereotype of these social groups. (Stereotype is defined as the knowledge we possess about, and associate with, a particular human social group.1) Thus, health care workers are taught to categorize individuals according to social groups so that patients may be accurately stereotyped along health-relevant domains.

Research in psychology has revealed that stereotypes, when factual, are an aid to information processing and facilitate accurate judgment and smooth social interaction.2 However, such research has also revealed that, unbeknownst to the perceiver, when the stereotype is invoked it also typically triggers inaccurate beliefs about the social group that ascribe predominantly negative qualities to the group and its members.3 For many social groups, the negative components of the stereotype are the more dominant association to the group, causing a person's overall reaction to a member of the group to be infused—unintentionally—with negative qualities. This is not the only unintended effect of categorizing people into social groups. These triggered negative components of the stereotype (which if they rose to conscious thought would be denounced and rejected) exert a well-established influence on perception, judgment, evaluation, and behavior.4,5 The effect is a dissociation between a person's conscious experience of being unbiased and a person's actual response, which is often guided by unconscious negative stereotypes. The influence of such unconsciously triggered negative and inaccurate components of a stereotype has been shown to bias judges’ sentencing decisions,6 employers' hiring decisions,7 teachers' evaluations of students,8 police officers' decisions to respond with shows of force,9,10 and people's judgments about one another's personality during everyday encounters.11

Like all other members of society, medical professionals know the social stereotypes of groups and thus are presumably subject to having stereotypes similarly unconsciously triggered. These implicit stereotypes could affect their diagnoses, treatment recommendations, expectations about whether a patient will follow a prescribed treatment, and both verbal and nonverbal behavior toward patients during professional interactions, despite their intention to avoid such biases in conduct. We therefore sought to illustrate that all aspects of stereotypes, not just the factually correct information, are triggered in the minds of medical doctors without their awareness.

A second unintended effect of categorizing a person as a group member is that the correct aspects of the stereotype can influence people at an undesired moment and lead to exaggerated and inaccurate judgments. It has been shown, for example, that expectations about a person unknowingly affect how a relevant behavior is identified: if we expect a person to be sad, we not only identify their tears as tears of sadness (as opposed to joy), but also infer an extreme amount of sadness (more than if no expectation had existed).12 We consciously experience our inference that the person is sad, but do not realize (1) the role our expectations play in producing that experience, (2) the role expectations play in delivering an inaccurate assessment of the degree to which the person is sad, and (3) the possibility that the expectation has led us to the wrong conclusion because the person may be shedding tears for another reason, such as joy or pain. Medical professionals are armed with such expectations by their accurate (and inaccurate) stereotypes, and thus, if stereotypes are activated, doctors can be led astray regarding both the severity of a patient's symptoms and the diagnosis—even if the stereotypical information they are using is perfectly correct. This is another reason we sought to establish whether medical doctors unknowingly allow stereotypes to guide their professional conduct.

Finally, categorizing people into groups leads to a host of affective or attitudinal consequences of which people may be unaware. We tend to dislike people from groups that are different from our own once we have brought group membership into play as a relevant domain with which to define a person, even when no real history of intergroup conflict or rational basis for such dislike exists.13,14 We also evaluate people from groups immediately and unknowingly, triggering what are referred to as implicit attitudes.15 Although explicit attitudes influence consciously controlled action, implicit attitudes guide nonverbal responses and other behaviors that are more difficult to control.16 For example, in an experiment by Green et al., physicians read the same vignette of a 50-year-old man with chest pain accompanied by an electrocardiogram suggesting he had anterior myocardial infarction.17 Half the physicians were shown a picture of a White patient, and the other half saw a picture of an African American man. The researchers found that implicit attitudes negatively influenced diagnosis and treatment recommendations (explicitly stated attitudes did not).

The psychological literature explains this implicit form of bias with a model of stereotyping5,11,18 that reveals it to unfold across a series of mental processes, or stages:

1. a person is identified and categorized as a group member (this can occur either consciously or unconsciously);

2. this is typically followed within 300 milliseconds by the unconscious act of retrieval from memory of the most dominant associations to the group (often the negative and positive elements of a group stereotype);

3. this stereotype is held in working memory outside of conscious awareness, attaining what is called a state of accessibility, and therefore more likely than other potential information to be used in directing subsequent cognitive, affective, and behavioral responses;

4. conscious responding is initiated and is moored to the unconscious stereotypes that were triggered, resulting in an undetected bias in how a person is perceived, evaluated, diagnosed, and treated; and

5. people may attempt to control the impact of the stereotype on their responses; the most common form of control is attempts to compensate or correct for the bias if it is detected (although control can occur even if bias is undetected2,3).

Our research focused on illustrating that stereotype accessibility occurs during the first 3 of these stages in a sample of medical doctors. The resulting mental state is a distinct phase of cognition that is dissociable from subsequent stages of cognition in which the accessible stereotype is used to shape an individual's response.5,18,19 A medical professional may remain naive to both a stereotype's accessibility and its use, but its accessibility is the more primary psychological event and must occur for a stereotype to bias reactions to a person. We focused on 2 questions relating to the accessibility of health care professionals’ stereotypes: (1) Are stereotypes made accessible without awareness whenever one person categorizes another as a member of a stereotyped group? (2) Does this unconscious event result in both the factual information associated with a group and the incorrect, undesired elements of the stereotype (which are explicitly rejected) attaining accessibility and heightened potential influence? We carried out 2 studies to answer these questions.

In recent years several empirical investigations have been conducted of how unconscious attitudes affect medical professionals.17,20 However, no study has examined whether doctors have stereotypes unconsciously triggered or the role that implicit stereotype activation has on diagnosis or treatment. We hypothesized that in addition to implicit attitudes (general emotional reactions), implicit stereotypes (specific knowledge about the group) are an underlying causal force that guides the differential reactions to minority and majority group members that were documented by the 2009 National Healthcare Disparities Report from the US Department of Health and Human Services.21 Although a small literature has accumulated that reveals that doctors' unconscious attitudes are triggered when encountering minority group members, these studies do not show that they also have stereotypes triggered. Such a finding would be foundational for linking the mental processes detailed in the multistage psychological model of stereotyping to health disparities.