When exposed to dangerous stimuli, such as potential predators, animals with amygdala lesions typically display a lack of the behaviors normally associated with the action program of fear [11
]. We used a comparable approach in SM by directly confronting her with fear-inducing stimuli and observing her behavior while also querying her subjective state. For ethical reasons, we chose three situations capable of inducing fear with little to no risk of direct harm to the subject: (1) visiting an exotic pet store with snakes and spiders, (2) walking through a haunted house, and (3) watching film clips of scary movies. SM provided her informed written consent to participate.
The first fear-inducing situation entailed direct exposure to snakes and spiders, two of the most commonly feared species in the animal kingdom. Interestingly, for many years, SM has repeatedly told us that she “hates” snakes and spiders and “tries to avoid them.” To test her real-life behavior, we took her to an exotic pet store and focused on probing for external manifestations of fear with a particular eye toward any signs of avoidance behavior. Upon entering the store, SM was spontaneously drawn to the snake terrariums and appeared visually captivated by the large collection of snakes. A store employee asked SM if she would like to hold a snake and she agreed (). SM held the snake for over three minutes while displaying a wide range of exploratory behaviors: she rubbed its leathery scales, touched its flicking tongue, and closely watched its movements as it slithered through her hands. Her verbal behavior revealed a comparable degree of fascination and inquisitiveness: she repeatedly commented, “This is so cool!” and asked the store employee numerous questions (e.g., “When they look at you, what do they see?”). During this time period, we asked SM to rate her fearfulness on a scale from 0 (no fear at all) to 10 (extreme fear). Her reported experience of fear never surpassed a rating of 2. Moreover, SM displayed a compulsive desire to want to “touch” and “poke” the store’s larger and more dangerous snakes, even though the store employee repeatedly told her that these snakes were not safe and could bite. In total, SM asked 15 different times if she could touch one of the larger snakes. She also attempted to touch a tarantula (), but had to be stopped due to the high risk of being bitten. When asked why she would want to touch something that she knows is dangerous and claims to hate, SM replied that she was overcome with “curiosity.” The disconnection between SM’s verbally stated aversion to snakes and spiders and her actual real-life behavior was striking. She did not display any signs of avoidance, but instead, exhibited an excessive degree of approach (a pattern highly reminiscent of the behavior in monkeys with Kluver-Bucy syndrome [12
]). We note that SM’s behavior was not merely the result of her feeling comfortable in the relatively safe environment of the pet store since we later discovered that, in the past, SM encountered a large snake outdoors and behaved in a similar manner (see supplemental information
The second fear-inducing situation attempted to scare SM in a setting professionally designed for such a purpose. During Halloween, we took SM to the Waverly Hills Sanatorium (), ranked as one of the “most haunted” places in the world [26
]. On an annual basis, the sanatorium hosts a haunted house, elaborately decorating the inside with eerie scenes, airing scary music and loud noises, and featuring people dressed as monsters, murderers, and ghosts. Upon arrival, SM and the research team were paired with a group of five women (all of whom were strangers). From the outset, SM voluntarily led the entire group through the haunted house, showing no signs of hesitation while walking around corners or into dark hallways. As the other members of the group lagged behind her, she would repeatedly call out, “This way guys, follow me!” The hidden monsters attempted to scare SM numerous times, but to no avail. She reacted to the monsters by smiling, laughing, or trying to talk to them. In contrast, their scare tactics typically elicited loud screams of fright from the other members of the group. More than showing a lack of fear, SM exhibited an unusual inclination to approach and touch the monsters. Ironically, SM scared one of the monsters when she poked it in the head because she was “curious” as to what it would feel like. Before, during, and after the haunted house, SM was queried about her current level of fear. She never reported experiencing any elevations in fear, her fear ratings being zero throughout. She did, however, report feeling a high level of excitement and enthusiasm. When asked to elaborate, she said her excitement was similar to the feeling she gets while riding on a rollercoaster, an activity which she claims to enjoy. In sum, SM was highly aroused by the haunted house, but did not feel any sense of fear, showed no signs of nervousness or apprehension while walking through dark passageways, and was never visibly frightened by any of the numerous attempts to scare her.
Lastly, we used a film induction procedure, widely considered one of the most effective and reliable ways to induce emotions in a laboratory setting [27
]. SM viewed a set of 10 different fear-inducing film clips (Table S2
). Interspersed between the fear clips were films aimed at inducing other types of emotion, including disgust, anger, sadness, happiness, and surprise. During the non-fear-related films, SM exhibited behaviors compatible with those emotions (e.g., laughter during happiness, shouts of revulsion during disgust) and reported experiencing high levels of the appropriate emotion (Figure S2
). By contrast, SM exhibited no fear responses and reported experiencing little to no fear across the entire battery of fear-inducing films (). Nonetheless, she found the fear films to be exciting and entertaining, and in one case, she inquired about the name of the movie so she could rent it from the video store later that day. Of note, SM commented that most people would likely feel scared by the content of the films, even though she did not; this provides evidence that her impoverished experience of fear can not be fully accounted for by a fear recognition deficit or a failure to understand the concept of fear (see supplemental information