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The history of life on earth goes back more than 3.5 billion years, with all life evolving from a common ancestor and diversifying to what we currently see on earth today.
The evolutionary history of a group of species is referred to as a phylogeny. The process of reconstructing a phylogeny is part of the science of systematics (the scientific study of biological diversity and its classification). Taxonomy is the science of classification (categorizing) and nomenclature (naming). Biologists prefer a system of classification that indicates evolutionary relationships among organisms. Cladistics is a method of classification in which organisms are categorized in groups (or clades) based on the most recent common ancestor. This methodology produces a phylogenetic tree that is a testable representation of the theoretical true phylogeny. Cladistics differs from historical methods of classification by relying on shared derived characters (a character shared by closely related organisms because they inherited it from their closest ancestor and which is not present in more distant ancestors) rather than overall similarity.
Our aim is to provide a focused discussion pertaining to diagnostic radiation usage and safety, with a focus on imaging modalities that use of x-rays.
Medical schools throughout the world emphasize radiological examination interpretation, but little is taught on the science behind these examinations and the potential harm from exposure to radiation.
We live in a world where everyone, and everything, is constantly exposed to non-ionizing and ionizing radiation. Ionizing radiation is electromagnetic energy that is capable of displacing electrons from the orbital rings of atoms, creating an ion. Ionizing radiation may arise from man-made activities or from natural sources. Natural sources of radiation include cosmic rays, isotopes in the ground, water, food (uranium, radium), or as a gas (radon).
From Structuralism to Functionalism
As structuralism struggled to survive the scrutiny of the scientific method, new approaches to studying the mind were sought. One important alternative was functionalism, founded by William James in the late 19th century, described and discussed in his two-volume publication The Principles of Psychology (1890) (see Chapter 1.2 for details). Built on structuralism’s concern for the anatomy of the mind, functionalism led to greater concern about the functions of the mind, and later on to behaviourism.
One of James’s students, James Angell, captured the functionalist perspective in relation to a discussion of free will in his 1906 text Psychology: An Introductory Study of the Structure and Function of Human Consciousness:
Inasmuch as consciousness is a systematising, unifying activity, we find that with increasing maturity our impulses are commonly coordinated with one another more and more perfectly. We thus come to acquire definite and reliable habits of action. Our wills become formed. Such fixation of modes of willing constitutes character. The really good man is not obliged to hesitate about stealing. His moral habits all impel him immediately and irrepressibly away from such actions. If he does hesitate, it is in order to be sure that the suggested act is stealing, not because his character is unstable. From one point of view the development of character is never complete, because experience is constantly presenting new aspects of life to us, and in consequence of this fact we are always engaged in slight reconstructions of our modes of conduct and our attitude toward life. But in a practical common-sense way most of our important habits of reaction become fixed at a fairly early and definite time in life.
Functionalism considers mental life and behaviour in terms of active adaptation to the person’s environment. As such, it provides the general basis for developing psychological theories not readily testable by controlled experiments such as applied psychology. William James’s functionalist approach to psychology was less concerned with the composition of the mind than with examining the ways in which the mind adapts to changing situations and environments. In functionalism, the brain is believed to have evolved for the purpose of bettering the survival of its carrier by acting as an information processor.  In processing information the brain is considered to execute functions similar to those executed by a computer and much like what is shown in Figure 2.3 below of a complex adaptive system.
Figure 2.3 Complex Adaptive System. Behaviour is influenced by information gathered from a changing external environment.
The functionalists retained an emphasis on conscious experience. John Dewey, George Herbert Mead, Harvey A. Carr, and especially James Angell were the additional proponents of functionalism at the University of Chicago. Another group at Columbia University, including James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth, shared a functionalist perspective.
Biological psychology is also considered reductionist. For the reductionist, the simple is the source of the complex. In other words, to explain a complex phenomenon (like human behaviour) a person needs to reduce it to its elements. In contrast, for the holist, the whole is more than the sum of the parts. Explanations of a behaviour at its simplest level can be deemed reductionist. The experimental and laboratory approach in various areas of psychology (e.g., behaviourist, biological, cognitive) reflects a reductionist position. This approach inevitably must reduce a complex behaviour to a simple set of variables that offer the possibility of identifying a cause and an effect (i.e., the biological approach suggests that psychological problems can be treated like a disease and are therefore often treatable with drugs).
The brain and its functions (Figure 2.4) garnered great interest from the biological psychologists and continue to be a focus for psychologists today. Cognitive psychologists rely on the functionalist insights in discussing how affect, or emotion, and environment or events interact and result in specific perceptions. Biological psychologists study the human brain in terms of specialized parts, or systems, and their exquisitely complex relationships. Studies have shown neurogenesis  in the hippocampus (Gage, 2003). In this respect, the human brain is not a static mass of nervous tissue. As well, it has been found that influential environmental factors operate throughout the life span. Among the most negative factors, traumatic injury and drugs can lead to serious destruction. In contrast, a healthy diet, regular programs of exercise, and challenging mental activities can offer long-term, positive impacts on the brain and psychological development (Kolb, Gibb, & Robinson, 2003).
Figure 2.4 Functions of the Brain. Different parts of the brain are responsible for different things.
The brain comprises four lobes:
- Frontal lobe:also known as the motor cortex, this portion of the brain is involved in motor skills, higher level cognition, and expressive language.
- Occipital lobe:also known as the visual cortex, this portion of the brain is involved in interpreting visual stimuli and information.
- Parietal lobe:also known as the somatosensory cortex, this portion of the brain is involved in the processing of other tactile sensory information such as pressure, touch, and pain.
- Temporal lobe:also known as the auditory cortex, this portion of the brain is involved in the interpretation of the sounds and language we hear.
Another important part of the nervous system is the peripheral nervous system, which is divided into two parts:
- The somatic nervous system, which controls the actions of skeletal muscles.
- The autonomic nervous system, which regulates automatic processes such as heart rate, breathing, and blood pressure. The autonomic nervous system, in turn has two parts:
- The sympathetic nervous system, which controls the fight-or-flight response, a reflex that prepares the body to respond to danger in the environment.
- The parasympathetic nervous system, which works to bring the body back to its normal state after a fight-or-flight response.
Research Focus: Internal versus External Focus and Performance
Within the realm of sport psychology, Gabrielle Wulf and colleagues from the University of Las Vegas Nevada have studied the role of internal and external focus on physical performance outcomes such as balance, accuracy, speed, and endurance. In one experiment they used a ski-simulator and directed participants’ attention to either the pressure they exerted on the wheels of the platform on which they were standing (external focus), or to their feet that were exerting the force (internal focus). On a retention test, the external focus group demonstrated superior learning (i.e., larger movement amplitudes) compared with both the internal focus group and a control group without focus instructions. The researchers went on to replicate findings in a subsequent experiment that involved balancing on a stabilometer. Again, directing participants’ attention externally, by keeping markers on the balance platform horizontal, led to more effective balance learning than inducing an internal focus, by asking them to try to keep their feet horizontal. The researchers showed that balance performance or learning, as measured by deviations from a balanced position, is enhanced when the performers’ attention is directed to minimizing movements of the platform or disk as compared to those of their feet. Since the initial studies, numerous researchers have replicated the benefits of an external focus for other balance tasks (Wulf, Höß, & Prinz, 1998).
Another balance task, riding a paddle boat, was used by Totsika and Wulf (2003). With instructions to focus on pushing the pedals forward, participants showed more effective learning compared to participants with instructions to focus on pushing their feet forward. This subtle difference in instructions is important for researchers of attentional focus. The first instruction to push the pedal is external, with the participant focusing on the pedal and allowing the body to figure out how to push the pedal. The second instruction to push the feet forward is internal, with the participant concentrating on making his or her feet move.
In further biologically oriented psychological research at the University of Toronto, Schmitz, Cheng, and De Rosa (2010) showed that visual attention — the brain’s ability to selectively filter unattended or unwanted information from reaching awareness — diminishes with age, leaving older adults less capable of filtering out distracting or irrelevant information. This age-related “leaky” attentional filter fundamentally impacts the way visual information is encoded into memory. Older adults with impaired visual attention have better memory for “irrelevant” information. In the study, the research team examined brain images using functional magnetic resonance imaging (fMRI) on a group of young (mean age = 22 years) and older adults (mean age = 77 years) while they looked at pictures of overlapping faces and places (houses and buildings). Participants were asked to pay attention only to the faces and to identify the gender of the person. Even though they could see the place in the image, it was not relevant to the task at hand (Read about the study’s findings at http://www.artsci.utoronto.ca/main/newsitems/brains-ability).
In young adults, the brain region for processing faces was active while the brain region for processing places was not. However, both the face and place regions were active in older people. This means that even at early stages of perception, older adults were less capable of filtering out the distracting information. Moreover, on a surprise memory test 10 minutes after the scan, older adults were more likely to recognize what face was originally paired with what house.
The findings suggest that under attentionally demanding conditions, such as a person looking for keys on a cluttered table, age-related problems with “tuning in” to the desired object may be linked to the way in which information is selected and processed in the sensory areas of the brain. Both the relevant sensory information — the keys — and the irrelevant information — the clutter — are perceived and encoded more or less equally. In older adults, these changes in visual attention may broadly influence many of the cognitive deficits typically observed in normal aging, particularly memory.
- Biological psychology – also known as biopsychology or psychobiology – is the application of the principles of biology to the study of mental processes and behaviour.
- Biological psychology as a scientific discipline emerged from a variety of scientific and philosophical traditions in the 18th and 19th centuries.
- In The Principles of Psychology (1890), William James argued that the scientific study of psychology should be grounded in an understanding of biology.
- The fields of behavioural neuroscience, cognitive neuroscience, and neuropsychology are all subfields of biological psychology.
- Biological psychologists are interested in measuring biological, physiological, or genetic variables in an attempt to relate them to psychological or behavioural variables.
Exercises and Critical Thinking
- Try this exercise with your group: Take a short walk together without talking to or looking at one another. When you return to the classroom, have each group member write down what they saw, felt, heard, tasted, and smelled. Compare and discuss reflecting on some of the assumptions and beliefs of the structuralists. Consider what might be the reasons for the differences and similarities.
- Where can you see evidence of insights from biological psychology in some of the applications of psychology that you commonly experience today (e.g., sport, leadership, marketing, education)?
- Study the functions of the brain and reflect on whether you tend toward left- or right-brain tendencies.
Watch the video: Biologie - Einführung in das Thema Evolution der Viren (November 2022).