Chapter 1.2 The boundaries and borders of psychology

The contributions of biopsychology and the sociocultural perspective.

Biology and culture establish both the possibilities and the constraints within which people think, feel and act. On the one hand, the structure of the brain sets the parameters, or limits, of human potential. Most 10-year-olds cannot solve algebra problems because the neural circuitry essential for abstract thought has not yet matured. Similarly, the capacity for love has its roots in the innate tendency of infants to develop an emotional attachment to their caretakers. These are biological givens.

On the other hand, most adults throughout human history would find algebra problems as mystifying as would a preschooler because their culture never provided the groundwork for this kind of reasoning. And though love may be a basic potential, the way people love depends on the values, beliefs and practices of their society. For example, in some cultures, people seek and expect romance in their marriages, whereas in others, they do not select a spouse based on affection or attraction at all. The study of psychological phenomena in other cultures by observing people in their natural settings is undertaken by psychological anthropologists, and cross-cultural psychology involves examining the patterns of behaviour across different cultures.

The boundary with biology and culture

The biological boundary of psychology is the province of biopsychology (or behavioural neuroscience), which investigates the physical basis of psychological phenomena such as memory, emotion and stress. Biopsychologists explore the role of biological factors in almost every area of psychology. Using sophisticated tools and technologies, psychologists who adopt this biological perspective examine behaviour through the lens of genetics and biological processes in the brain and other parts of the nervous system. Since its origins in the nineteenth century, one of the major issues in behavioural neuroscience has been localisation of function, or the extent to which different parts of the brain control different aspects of functioning. In 1836, a doctor named Marc Dax presented a paper suggesting that lesions on the left side of the brain were associated with aphasia, or language disorders. The notion that language was localised to the left side of the brain (the left hemisphere) developed momentum, with new discoveries linking specific language functions to specific regions of the left hemisphere. Paul Broca (1824–1880) discovered that brain-injured people with lesions in the front section of the left hemisphere were often unable to speak fluently but could comprehend language. Carl Wernicke (1848–1904) showed that damage to an area a few centimetres behind the section Broca had discovered could lead to another kind of aphasia. These individuals can speak fluently and follow rules of grammar, but they can neither understand language nor speak in a way that is comprehensible to others (figure 1.1). Individuals with this form of aphasia might speak fluently, apparently following rules of grammar, but their words make little sense (e.g., ‘I saw the bats and cuticles as the dog lifted the hoof, the pauser.’).

Contemporary neuroscientists no longer believe that complex psychological functions ‘happen’ exclusively in a single localised part of the brain. Rather, the circuits for psychological events, such as emotions or thoughts, are distributed throughout the brain, with each part contributing to the total experience. A man who sustains lesions to one area may be unable consciously to distinguish his wife’s face from the face of any other woman — a disabling condition indeed — but may react physiologically to her face with a higher heart rate or pulse (Bruyer, 1991). Technological advances over the last two decades have allowed researchers to pinpoint lesions precisely, and even to watch computerised portraits of the brain light up with activity (or fail to light up, in cases of neural damage) as people perform psychological tasks.

For example, research shows that genes influence many aspects of our behaviour, including how kind we are to other people or whether or not we are likely to own a dog. A recent study examining 35 035 twin pairs found that genes explain more than half of the variation in dog ownership, showing that the choice of owning a dog is influenced by our genetic make-up (Fall et al., 2019).

In contrast to biopsychologists, however, psychologists who adopt a sociocultural perspective emphasise the social interactions and cultural determinants of behaviour and mental processes. Although we are often unaware of their influence, factors such as ethnicity, religion, occupation and socioeconomic class all influence our mental processes and behaviour. A sociocultural perspective emphasises social interaction and the cultural determinants of behaviour and mental processes. Cultural psychologists focus on the patterns in behaviours and how culture influences those behaviours; cross-cultural psychologists focus on the patterns — the similarities and differences — among various cultural groups and how they influence behaviours.

Biopsychology (or behavioural neuroscience) examines the physical basis of psychological phenomena such as motivation, emotion and stress. Although different neural regions perform different functions, the neural circuits that underlie psychological events are distributed throughout the brain and cannot be ‘found’ in one location. At another boundary of psychology, the sociocultural perspective emphasises social interaction and the cultural determinants of behaviour and mental processes. Cultural psychology focuses on how culture influences patterns in behaviours, while cross-cultural investigation tries to distinguish universal psychological processes from those that are specific to particular cultures.