a decrease in social interactions. Not only were these behavioral characteristics just outlined and their follow-up was brief, but they were also certainly biased by pre-existing mental disorders.
War Times, Questionnaires, and Group Studies
World War I sadly supplied much data for the understanding of personality changes due to brain trauma [16]. However, World War II triggered more systematic and larger-scale assessments: Interviews and questionnaires with features amenable to quantification and scoring thus resulted in first group studies.
Large cohort studies with patients based on war records were carried out retrospectively. For instance, Lishman examined psychiatric and behavioral disabilities after head injury from the Oxford collection of head injury records, compiled during World War II [17]. A detailed follow-up was available up to 5 years after the acute stage for most patients, much of this material consisting of questionnaires listing a wide range of symptoms. In Lishman’s study, altered behavior was part of the category “psychiatric disability” defined “as disturbance in any area of mental life, as reflected by impaired intellectual function, disorder of affect, disorder of behavior, somatic complaints without demonstrable physical basis, and/or formal psychiatric illness.” Affective disorders consisted of depression (episodic or continuous), emotional lability, morbid anxiety and phobias, irritability, overt aggression, apathy, loss of initiative and euphoria, whereas behavioral disorders involved crime or misdemeanours, sexual disturbance, lack of judgment, reliability, consideration for others, childish or facile behavior, restlessness, impulsiveness, and disinhibition. Likewise, Grafman et al. [18] retrospectively investigated the presence of aggressive and violent behavior in veterans who suffered a penetrating brain injury during their service in Vietnam. Besides an open question asked by the neurologist (“Have you ever had any violent behavior against persons or things? We all lose our temper now and then, but have you ever beaten someone up or torn up a room?”), the veteran and family members completed questionnaires. It included the Beck Depression Inventory [19], the Katz Adjustment Scale (relatives’ judgment of the subject’s competency across a variety of social and behavioral domains) [20], and the VHIS Family Questionnaire (addressing the relatives’ ability to cope with the subject’s behavior). Finally, the examiner filled in the Neurobehavioral Rating Scale, an inventory sensitive to aberrant behavior [21]. Overall, questionnaires were quantitative, interrogated patients and relatives, and therefore led to more systematic assessments. This set-up allowed the evaluation of behavioral deficits on large cohorts of individuals, as well as conducting follow-up investigations to shed light on the long-term outcome of patients.
1980–1990s, Innovations and Emergence of Social Cognition
A key factor in the 1980s is a change of perspective: it was realized that certain symptoms occurring in real life cannot be pinpointed with classical “laboratory” tests nor in the examination room. In other words, formal neurological/neuropsychological assessments can (1) miss certain behavioral impairments, and can (2) exert external constraints and conditions that differ sufficiently from daily life as to impact test results. This notion introduces the concept of “ecological validity.” Moreover, coming back to our neurological definition of behavior, the last decade of the 20th century has seen the emergence of a specific field dedicated to the study of cognitive processes required in social behavior, referred to as “social cognition.”
This new perspective is illustrated, for example, by the characterization of “imitation and utilization behavior,” a disturbed response to external stimuli which belongs to the “dependency syndrome” [22]. Lhermitte [23] thus established fairly unusual and innovative methodology to study the presence of this phenomenon in patients with cerebral lesions. In stark contrast to classical examination settings, the examiner remains neutral and indifferent to the patient during the whole examination, and then makes a series of gestures, such as body, symbolic and gymnastic gestures, gestures involving objects, and pronounces short sentences, sings, writes and draws. The patient is told not to copy the examiner, who then repeats his sequence of gestures. The patient’s behavior is observed and evaluated. To better understand the impact of the environment on the dependency syndrome, the study went a step further by taking the patients outside the examination room, filming and photographing all steps [23]. The patient was thus put in situations of everyday life (e.g., doctor’s office, garden, gift shop). Although creative, less structured and probably more ecological, this methodology obviously poses ethical issues with respect to the patient and his family.
The discrepancy between good performance in classical tests in the examination room and successive failures in daily life observed in some patients has led scientists to address those mechanisms which are impaired and cause emotional and behavioral changes. Before the availability of dedicated tests, such investigations made use of personality trait inventories [5, 24] and tools from developmental psychology [5, 25, 26]. In these studies, tasks targeted different components of social behavior, namely self vs. others perspective, social knowledge, and moral reasoning. All of them consisted of standardized verbal presentations of moral dilemmas or social situations that required verbal responses. Inspired by these studies, new paradigms have been designed, in particular to evaluate “pseudopsychopathy” [16], later called “acquired sociopathy” [13]. This term refers to individuals developing high levels of aggression and antisocial behavior with reduced empathy and guilt after acquired lesion to the orbitofrontal cortex. This is, for example, the case of patient EVR who underwent a resection of a large orbitofrontal meningioma compressing both frontal lobes [5]. Previously, a sensible and successful fellow, EVR changed dramatically after surgery; he separated from his family, became unable to hold a job and made unreasonable decisions. The integrity of his knowledge of normal patterns of social behavior and its application were measured. Despite his ability to reason appropriately about moral problems that were presented to him, and a performance in social cognition tasks that lay in the range of (or even excelled) healthy controls, he was unable to apply such reasoning in real-life situations [5, 13]. Of note, despite their social nature, these tasks do not seem to sufficiently match real-life situations for several reasons (e.g., verbal tasks vs. multimodal inputs, observer vs. protagonist in real life), thus suggesting that a decision-making disorder lies at the core of the impairment. The social knowledge and access to it was preserved, yet EVR failed to apply the appropriate choice-making strategy. These observations were further developed in the “somatic marker hypothesis” [13], which denotes the covert influence of a somatic process on decision-making, as suggested by Luria thirty years before [11]. To validate this hypothesis, “reversal learning” tasks were developed, such as the Iowa Gambling Task that mimics real-life
