Free Methods of Persuasion: How to Use Psychology to Influence Human Behavior by Nick Kolenda

students to frown, which decreased blood flow and heightened brain temperature, thereby dampening their mood. The mere act of smiling can spark biological mechanisms, which can then trigger attitudes and emotions that we associate with smiling.
    Even if particular body language doesn’t directly trigger biological responses that alter our mood (e.g., smiling lowers brain temperature, which enhances our mood), our body language can still influence cognitive mechanisms because of self-perception theory.
    Self-Perception Theory. Self-perception theory proposes that we sometimes infer our attitudes by examining our behavior (Bem, 1972). If we hold an ambiguous attitude toward something, we try to make sense of that attitude by examining our actions and body language. For example, when people viewed photographs of celebrities, they perceived them to be less famous when they were asked to view the pictures while furrowing their eyebrows, a facial expression associated with exerting mental effort (Strack & Neumann, 2000). When people furrowed their eyebrows, they inferred from their facial expression that they were exerting mental effort to think of that celebrity, an inference that led them to perceive the celebrities to be less famous.
    If there’s ever inconsistency between our attitudes and body language, we tend to trust the latter. Consider a clever experiment from the 1960s (Valins, 1967). A researcher told a group of males that he would be measuring their heartbeats in response toward sexual images and that they would be hearing their heartbeat while viewing the photos. However, the men were told that this audio was merely due to poor equipment and that they should ignore the sound of their heartbeat (you should keep in mind that this study was conducted in 1967, when technology was just slightly less developed . . .).
    During the experiment, the men were shown 10 pictures of females from Playboy , and they heard their “heartbeat” increase on 5 of those 10 pictures (when in actuality, the sound was fake and controlled by the researcher). The results were quite surprising: the men found the females more attractive when their heart rate had supposedly increased. This influence was so strong that the males still chose those same photographs when they were asked again 2 months later. Thus, even when biological responses are inaccurate (or even fake), we still tend to trust that feedback by developing attitudes that are congruent with those responses. As you’ll learn in the next chapter, self-perception theory plays an even more powerful role when it comes to behavior (i.e., not just body language).
    PERSUASION STRATEGY: CONTROL BODY LANGUAGE
    Due to our tendency to associate certain body language with certain attitudes (e.g., we associate head nodding with open-mindedness), this section proposes that getting your target to exude certain body language can cause your target to develop certain attitudes that would be favorable for your persuasion. In the following sections, you’ll learn some specific types of body language that would be favorable for you to extract, and you’ll learn some clever techniques to subtly extract that body language from your target.
    Head Nodding. With a few rare exceptions (e.g., some parts of India and Africa), head nodding is a widespread symbol for agreement. When people are engaged in a conversation, they’ll occasionally nod their head to show that they’re interested in what the other person is saying, and it serves as a nonverbal cue for the speaker to continue talking. Due to this heavy association with agreement, getting your target to nod his head before you make your request can trigger a more agreeable and open-minded attitude.
    Supporting that claim, Wells and Petty (1980) gave students a pair of headphones and asked them to listen to a radio broadcast. They asked the students to test the quality of the headphones by either nodding their head up and down or by shaking their