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Social Psychology. Daniel W. Barrett
Читать онлайн.Название Social Psychology
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isbn 9781506310626
Автор произведения Daniel W. Barrett
Издательство Ingram
The second source of variation is mutation, which is the result of random errors in the duplication of genes within a given individual. Mutations typically produce recessive alleles, are “invisible,” and are generally not adaptive. These mutations will only “appear” if the carrier reproduces with another carrier of the same gene (such as a close relative). However, mutations occasionally create both dominant and adaptive genes and, if the carrier successfully passes them down to the offspring, then they may eventually become present in the entire population. Dominant genes (such as for brown eyes) are expressed if the parts of a pair of genes are different, but the expression of recessive genes (such as for blue eyes) only occurs when both halves of a pair are identical. Psychological tendencies and personality traits, such as extraversion or conscientiousness, are partially inherited in much the same way.
Although we tend to think about the evolution of genes in terms of natural selection, recent research suggests that advances in culture have also affected the evolution of genes. In other words, genes and culture have coevolved and together have produced the human mind as we know it today (Chiao, 2011; Richerson, Boyd, & Henrich, 2010). Cultural variation in diet and disease exposure have affected specific alleles, such that these alleles differ in prevalence across cultures. For instance, differences in the desirability and frequency of culture-related traits like individualism-collectivism may be correlated with genetic variation (Fincher, Thornhill, Murray, & Schaller, 2008). Later we discuss the role that disease may have played in the historic development of collectivistic cultures (see Chapter 6). The takeaway message here is that not only can genes affect social behavior, but also that social behavior can impact genes.
Alleles: Gene variants that carry the information essential for the expression of traits
Think Again!
1 What is a gene? An allele?
2 What is a chromosome?
3 How can a single gene mutation affect evolution?
Doing Research: Methods Of Social Neuroscience
Not that many years ago scientists had only relatively primitive tools available to study the brain and consequently could only guess at the physiological processes that underlie social behavior. Fortunately, technologies developed in recent decades have led to exponential growth in our understanding of how the brain works. Today, social neuroscientists employ a range of methods and technologies that vary in cost, accessibility, complexity, frequency of use, invasiveness, and what they measure. In this section I will touch on a few that are the most useful for introductory social psychology students.
Galvanic Skin Response
When you are nervous or anxious, does your heart beat a little faster and do you sweat a bit more? Well, early research in physiological psychology focused primarily on measuring relatively obvious overt bodily responses to situations and stimuli. One of the most researched psychophysiological constructs targeted by social neuroscience was arousal (Cacioppo, Berntson, & Crites, 1996). When we are physiologically aroused, we typically experience increased heart rate, blood pressure, pupil dilation, and sweating. The primary method for assessing arousal was the measurement of skin conductance or galvanic skin response (GSR). GSR—more recently labeled electrodermal activity or EDA—is used as a measure of arousal, because arousal induces the individual to produce a small amount of sweat, even if that person cannot detect it (Mendes, 2009).
Typically, two electrodes are placed on the hand, a weak electrical current is applied, and the time it takes for the electricity to pass from one electrode to the other is measured. An increase in skin conductance (faster transmission of current across the skin) occurs when a person sweats and suggests that the person is aroused (unless her hand is moist for some other reason). The polygraph or lie detector measures GSR and other indices of arousal but is famously unreliable as way to determine the veracity of a person’s testimony or answers. The primary reason for this is that a person’s arousal could be caused by any number of factors, only one of which is lying (see Chapter 5 for more on lie detection). For instance, a person may become aroused simply because he is being asked about whether he is lying.
Electromyography
Electromyography (EMG) also measures electrical activity but does so by detecting muscle movements instead of surface skin conductance. Social psychologists have employed EMG to measure muscle movements in the face that are thought to reflect emotional and/or attitudinal states, and self-reports of depth of message processing (Cacioppo & Petty, 1981). The underlying rationale is that the activity of specific muscles is correlated with verbal self-reports and behavioral measures, and thus the EMG can provide additional evidence of cognitive and affective processes (Blascovich, 2000; Blascovich & Seery, 2007). For instance, Cacioppo and Petty (1981) describe how increased movement (and electrical activity) of facial muscles associated with speech parallel other measures of deeper processing of persuasive messages. As we’ll discuss in Chapter 7, how carefully we examine the arguments in a message impacts how much we are persuaded by them. It is fascinating that our facial muscles can reflect whether or not we are thinking deeply or superficially! Facial EMG can also detect the positivity or negativity of emotional reactions and the intensity of those reactions among message recipients during message exposure (Cacioppo, Petty, Losch, & Kim, 1986). Social psychologists have utilized facial EMG in research on the mere exposure effect (see Chapter 11) (Harmon-Jones & Allen, 2001), stereotyping (see Chapter 10) (Vanman, Saltz, Nathan, & Warren, 2004), and other topics in social psychology (Bartholow & Dickter, 2007; Hess, 2009).
Electroencephalography (EEG) and Magnetoencephalography (MEG)
An EEG measures electrical activity generated by the brain, whereas an MEG targets the magnetic signals associated with electrical output. You have most likely read about EEG in your introduction to psychology course in the context of measuring brain wave patterns as a way to identify and track the stages of sleep. EEGs are also used to record abnormal electrical activity associated with epilepsy. Regardless of its purpose, an EEG is conducted by placing electrodes at numerous places on the scalp in order to detect brain wave patterns. Social psychologists are specifically interested in how the brain responds to particular social stimuli and therefore focus on changes in the electrical activity, called event-related potentials (ERPs), during and immediately after stimulus presentation. These stimuli can be visual, auditory, olfactory, or tactile (Cacioppo, Lorig, Nusbaum, & Berntson, 2004).
A patient undergoes an electroencephalography (EEG). EEG examines the electric activity of the brain using electrodes placed at key places on the skull.
C3336 Klaus Rose Deutsch Presse Agentur/Newscom.
Given that ERPs are fairly weak and can easily be drowned out by baseline electrical activity, researchers enhance signal detection by gathering data over many trials and averaging the data from multiple