Psychophysics, Psychology and the Investigation of the Mind - Essay Example

?Running head: PSYCHOPHYSICS Psychophysics, Psychology and the Study of the Mind of Ernst Weber's law, that equal relative increments of stimuli manifest themselves in equal proportion to increments of sensation is fundamental for psychic measurement. The law, however, forms only the basis for measurement, and while important, it should not be viewed as singular to the measurement process. Relationships between stimulus increments and sensation increments in general are determined not only within the parameters of Weber’s law, but also outside of it. In the quest then for accurate psychic measurement, methods beyond the law must be considered in the interests of more accurate, useful and meaningful psychic measurement. (Fechner, 1912) Psychophysics: It’s Roots in Fechner and Weber As stated, quantitative scientific study of the relation between stimulus and sensation is, more to the point, the manual manipulation of stimulus properties for the purpose of analyzing perceptual processes of reaction to stimuli. Today, the area of modern psychophysics is seen as applying a whole class of methods evolved over time to the empirical study. Methods, for instance, such as absolute threshold can measure such sensory reactions as a subject’s ability to perceive a dim light in a dark room by manipulating the intensity of the dim light. (Zimbardo et al, 2010). While Gescheider (1997) found that modern applications tend to rely heavily on ideal observer analysis and signal detection theory, the work of Ernst Heinrich Weber and Gustav Theodor Fechner, particularly Fechner as described in his 1912 treatise, Elemente der Psychophysik, remain the basis of new developmental processes. The classical techniques and theory of psychophysics were formulated by Fechner. Applying laws of physics and mathematics, he took Weber’s basic law of measuring the proportional aspects of stimuli a step further, using logarithmic relation between physical and psychological (or perceived) magnitudes—measuring statistically how individuals actually perceived stimuli, or understood it, in relationship to behavior. In considering the significance and practical consequences of access to such information, Zimbardo et al (2010) offer the example of the usefulness of knowing how loud a fire alarm must be for those inside a building to hear it. This particular example speaks to the importance of the hearing system in determining the impact of stimuli; the former example of perceiving a dim light in a dark room speaks to the visual system, which we focus on for the purpose of analyzing its importance to the measurement of stimuli and its effect. The Visual System The visual system as related to sensory reception is perhaps the most studied of all methods. Simplified, the eye gathers light, focuses it, and sends signals to the brain. For instance, Zimbardo et al (2010) found that color is literally created through neural processes of the brain as it interprets information from the original source. Hecht (1924) in his study of visual discrimination similarly found that sensory determination in changes of brightness and in discriminatory thresholds versus original light intensity can be calculated by mathematical formulas. These formulas over time, evolved and were incorporated into the Weber-Fechner law, combining “Weber’s Law that over a large dynamic range, and for many parameters, the threshold of discrimination between two stimuli increases linearly with stimulus intensity...[and Fechner’s work] showed [ing] how Weber’s law could be accounted for by postulating that the external stimulus is scaled into a logarithmic internal representation of sensation” (Dehaene, 2003:146). Using information on the magnitude of star light and its ratio to intensity, Fechner (1860) was able to determine the relation between the two, and as suggested by Hecht (1924), thus developed the idea that this relationship produces a human threshold sensation leading to the perception of varying degrees of light. Interesting studies have been done by sensory physiologists on the receptive fields [the area in the visual field from which it receives stimulation] of cells in the visual cortex. As found by Zimbardo et al (2010, “…cells at different levels of the visual system respond most strangely to different patterns of stimulation.” (107). The division into subdivisions of nerve ganglia make the brain capable of performing many visual tasks while analyzing to its satisfaction a complete picture or perception of an image. Hence, while the visual processes are simultaneously at work, they have one common goal, to present to the brain a sensory perception of the whole. In terms of light perception, cells responsive to the receptive field are those most stimulated by light and visa versa. Perhaps the most interesting aspect of the visual system seems a simplistic explanation: “experiences of form, color position and depth are based on processing the same sensory information in different ways” (Zimbardo, 2010:108). Even in blindness, with sensory receptor cells non-functioning, other cells are available for stimulation, hence the enhanced sensory sensibility of blind people, or a heightening of other senses to compensate for those lost. The Attentional Process Attentional processes, as might be inferred, are the processes by which individuals determine what to focus on and what they learn through that observation. They are highly related to stimuli, its sensory focus and function. Active attention involves many cognitive processes, including the act of selecting and focusing on what the brain considers important at that particular moment. We may be at a baseball game but two men arguing several rows below us have garnered our attention. Focusing on them takes intentional choice. Of the many things we could be focusing on in a stadium filled with thousands of people, we’ve chosen to place our attention on these two individuals. In closely observing the two, we may find their argument is friendly. In short, the more you attend to the object of focus, the more you learn about it. Attention comes in two ways: you focus on something because in some way it satisfies a person goal. For instance, one might like the idea of and look for fans arguing at sports events, so the previous choice makes sense. It may have been your goal to find such action in going there. On the other hand, should a fan several rows down turn suddenly and begin shouting at you because you are rooting for the other team, that person has captured your attention. The first, “goal directed selection” reflects the attention choices an individual makes; the second, “stimulus driven capture occurs when... objects in the environment [conversely]...capture your attention” (Zimbardo et al, 2010: 121) As research suggests, the latter attention getter seems more urgent and thereby exerts more influence on our attention than the former stimulus. The long and short of it is that it is difficult to avert attention away from a shouting, confrontational fan. Classical Conditioning: Pavlov’s Dog and Beyond The term “classical conditioning” generally refers to a process of behavior modification by which a subject comes to respond in a desired manner to a previously neutral stimulus that has been repeatedly presented along with an unconditioned stimulus that elicits the desired response. The most recognized study in this area was conducted by Russian physiologist, Ivan Pavlov. Pavlov, who was actually studying digestive systems in dogs, came upon the conditioning aspect by accident. As he had his assistants feed the animals powdered meat as part of the initial experiment, he began to notice that even without seeing the meat, and the dogs would begin to salivate at the site of the assistants. A neutral stimulus had acquired the capacity to elicit a response through association with a stimulus that already elicits a similar or related response. They were becoming conditioned to exhibit certain behavior based on this secondary stimuli (i.e., the often heard remarks in jest about those easily manipulated into certain behavior by certain stimuli). A person who may have gotten very ill after eating some bad chicken will refrain from ever eating chicken, no matter how fresh. It is the chicken itself which has made them sick, not the bacteria in the chicken which was not fresh. The reaction to this stimuli is that every time the person sees a plate of chicken, they become nauseated. Beyond the two stimuli, generalization of stimuli to elicit the person’s nausea may extend itself to the restaurant where the chicken was eaten, or to some extent, perhaps, poultry in general. With discrimination training, a subject can learn to determine which stimuli triggers the strong response, and which is the weaker and thus ignore it. Through discrimination training [conditioning] then, a subject can be either taught to react to a particular stimulus, or dissuaded from reacting by understanding which signals may be valid, and which may not be. The subject becomes discriminating. Generalization and discrimination [when it comes to stimuli] must strike a balance” (Zimbardo et al, 2010: 172). You don’t want to ignore the possibility of food poisoning but neither do you wish to live with a generalized reaction that all chicken will make you sick, or that the chicken served in all restaurants will do the same. In this case, the chicken is the unconditioned stimulus (UCS); the restaurant or conditioned stimulus (CS) elicits the behavior of nausea. Discrimination between the two responses is important to be learned, and the subject must be “deconditioned,” as it were, not to become nauseated when eating in all restaurants, whether eating chicken or not. This is done by manipulating the stimuli. In short, classical conditioning can be used to both understand behavior and its stimuli, and by manipulating stimuli, adjust it. From a psychoscientific perspective, it is both the understanding of the neural processes that produce reactions, and control of those processes that can affect positive change in the behavior. Conclusion For much of the earlier part of the 20th century the study of neural processes were viewed as quite separate from the practice of psychology. A “never the twain shall meet” attitude existed.Understanding the processes of the mind was a matter of mathematical theories having little if nothing to do with psychology. Today we know better. New cognitive neuroscience and psychological observations are intrinsically combined in experiments. Weber and Fechner’s Law coexists side by side with Pavlov, providing a holistic approach to the mind, how it functions, and how it can be regulated. References Dehaene, S. “The neural basis of the Weber–Fechner law: A logarithmic mental number line.” Trends in Cognitive Sciences, 7 (4): 145-147. Fechner, G.T. (1860). “Elements of Psychophysics, Sections VII and XVI”. (Herbert Sidney Langfeld, Trans). Classics in the History of Psychology. Retrieved online 2 February, 2011 from http://psychclassics.yorku.ca/Fechner/ Gescheider G (1997). "Chapter 5: The Theory of Signal Detection". Psychophysics: the fundamentals (3rd ed.). Mahwah, New Jersey: Lawrence Erlbaum Associates. Hecht. S. (1924). “The visual discrimination of intensity of the Weber-Fechner law.” Harvard University: Department of Physical Chemistry in the Laboratories of Physiology. Retrieved 4 February, 2011 from: http://jgp.rupress.org/content/7/2/235.full.pdf Zimbardo, P.G. and Gerrig, R. J. (2010). Psychology and life (19th ed.) Boston: Allyn and Bacon. Read More