Brain and Smell Essay

Submitted By MagnaCartaHolyGrail
Words: 2778
Pages: 12

Chapter 1 – Principles of Perceptual Measurement
1. Psychophysics began with Gustav Fechner in 1860. He wanted to determine the relationship between the mind and body. In doing so he established not only guiding principles in this new area of study but he also developed a set of experimental methods as well. The methods were:
Method of adjustment – this is considered to be the quickest method. What this involves was simply asking the human subject to adjust the physical intensity of a stimulus so that it is barely noticeable.
Method of limits – due to a higher level of accuracy than the method of adjustment, this experiment takes more time. Here the physical it taken from an ascending of descending list that moved up or down accordingly so that the stimuli disappears.
Method of constant stimuli – this method provides the most accurate data. Here the human subject is presented with intensity values that are randomly chosen from a preset range.
I thought it was important to mention Gustav because he was an early pioneer in experimental psychology as well as the founder of psychophysics.
2. Levels of stimulus
Absolute threshold – this is the minimum level of stimulus that we can detect.
Subthreshold – any stimulus below this level we cannot detect.
Suprathreshold – this is any stimulus that is above the absolute threshold in which we can detect.
Difference threshold – this is the smallest change in stimulus that required to produce a discriminable change in sensation.
These thresholds are very important to learn early on because they’re the standardized levels used in many experiments found in psychophysics.
3. Fechner believed that sensations could only be measured indirectly through different thresholds. However, Stanley Smith Stevens believed that the exact relationship between stimulus and sensation could be directly obtained. As a result of this challenge Stevens developed a set of procedures known as scaling. Here, subjects were asked to give a direct rating of the sensation they experienced. This method is currently known as magnitude estimation and it has a high level of consistency.
I thought this point was important because it shows progression though this field of study. William James said that sensation simply could not be measured and Stevens proved were.
Thing to Remember – one piece of information that I will take with me from this chapter is the benefit of quantitative relationships between physical and perceptual. As a marketing undergrad I can fully appreciate the idea of putting a number on the perceptual quality of a stimulus. The example was given about a company trying to test its aromatic acceptance of a perfume; I would assume that a company would love to figure this out before they put a new product into production which can cost millions of dollars.
Chapter 2 – Biological Foundations of Sensory Perception
This chapter is all about the brain and its different segments, functions at the cellular level, and the techniques used to study its functions.
1. The chapter starts with a little history starting with Austrian physician Franz Joseph Gall who believed that all mental functions can be precisely localized to certain parts of the brain. Gall proposed that the human brain was divided into precise anatomical modules in which each of them were for different mental functions. Additionally, he believed that the bumps and depressions in the skull was related to the underlying brain matter. If the patient had bumps then he assumed that part of the brain was well developed.
I found this to be interesting because like many of the early individuals, I see Gall as a pioneer. Based on his studies he the field of study called phrenology was born in which I found to be important.
2. I found it interesting that even at the beginning of the 20th century there were still a number of highly influential scientists that still did not believe in Gall proclamation that the brain was divided into