Is Psychology a Science? Theories and Research Methods

Is Psychology a Science? Theories and Research Methods Is psychology a science? Discuss with reference to scientific method and bias in psychological research. Psychology can be viewed in a variety of ways as accords to the many schools of thought that pertain to psychology. From its origins in philosophy, psychology has undergone a variety of classifications. The major scientific paradigms born from philosophical enquiry were the school of empiricism and the school of rationality. Essentially, these two approaches dictated the direction that psychology must take if it was to be regarded as scientific. One of the first schools of thought in psychology was heavily concerned with its reputation as a scientifically validity enquiry. This was to be known as the behavioural approach to psychology or the behavioural perspective. The behavioural perspective was devised by Watson who used observation to determine evidence. As a consequence of according to the governing principles of objective scientific research, Watson rejected the notion of any internal psychological mechanisms as he believed that this could not be quantifiably measured (Miell et al, 2002). All Watson was interested in was the observable external phenomena, which meant the analysis of behaviour. Consequently, Watson placed an emphasis on psychology as primarily a learning phenomenon. A fundamental distinction that occurs within behaviourism is within this role of learning. Essentially, two approaches formed called classical and operant conditioning. Research into classical conditioning was defined by physiologist Pavlov who was also concerned with scientific analysis. Pavlov observed that in relation to certain stimuli dog’s behaviour could be conditioned through association (Miell et al, 2002). Using a dogs’ biological respons e to hunger, Pavlov was ble to scientifically demonstrate that there was a basic relationship between an observable stimulus and the animals learned response. Whilst in operant conditioning, Skinner was able to ascertain that there was a pre-conceived notion in the environment that led the animal to learn through a process of trial and error, which led to observable schedules of behaviour (Skinner, 1946/1990). In both classical and operant conditioning we can see that learning is defined as a scientifically observable and so provable modification of behaviour caused by association and manipulation of the environment. However, this approach clearly lacks greater insight into the role of the mind, its cognitive processes and also suffers from being based upon animal and not human studies. The cognitive approach addresses the human capacity to categorise, generalise and conceptualise certain phenomena. Primarily concerned with the functioning of the mind itself it engaged in the scientific analysis notions such as memory, perception and categorisation (Miell et al, 2002). Unhappy at the flaws in behavioural psychology, cognitive psychologist Bruner, devised a test to see how we mentally constructed categories. Unlike the objective approach of conditioning, Bruner suggested that this was an engaging intelligent procedure that was performed by way of hypothesis testing stages of acceptance and rejection based upon trial (Bruner et al, 1956). To be valued as scientific, a test involving a variety of shapes were used in a variety of conditions. Some of these conditions shared the same number of shapes, some the same colour of shape, whilst others shared the same number of borders. No two varieties were identical. From the results of this experiment, Bruner was able to sur mise that there were tw forms of cognition that had been present. Successive scanning, which tested one hypothesis at a time and conservative scanning, which sought to eliminate classes of hypotheses (Bruner et al, 1956). Unlike the behavioural approach, we can see from the findings and classifications of these studies that an attempt is being made to understand the intelligent human mind with regards to categorisation. However, categorisation is not accepted by everyone in the field of science and its objective validity does suffer from critical enquiry. For instance, addressing the empiricism versus rationalism argument, many have argued that the categories in the study are innate rather than learned (Chomsky Fodor, 1980). This strengthens the behavioural notion that the conceptual structure of the mind is open to interpretation, and so cannot be considered an entirely scientific approach to psychology. Another school of thought within psychology is that concerned with the social aspect. This is primarily interested in the role that social influence has on our behaviour. For instance, in the findings of a test put forward by Sherif, we can see the extent to which people will use the word of others and the resource of group norms to ascertain a truth about something. This is an important concept with regards to the influence of social norms as we can observe that our psychology is influenced by our conformity to social norms (Sherif, 1936). Similarly, a test devised by Asch revealed that conformity of an individual to a norm was indicative of individual identity (Asch, 1956). Similarly, research by Baron indicated that through a lack of responsibility that an individual felt to correct and deviate from a social norm an account could be made to configure their potential to conformity (Baron et al, 1956). Essentially, these tests revealed that the role of responsibility was based upon conscriptions o social norms, attitudes, beliefs and ideologies. However, these findings suffer from being based upon social norms and cultural constructs such as identities and beliefs and so cannot be considered universal, objective principles that would accord to the main scientific schools such as physics and chemistry. Another key school of thought is psycho-analysis and developmental psychology. Stemmed from Freudian theory, psycho-analysis and developmental psychology is concerned with the development of the subject’s personality in relation to underlying motives and mainly sexually based desires and conflicts (Freud, 1917/1973). Using a notion of base primordial drives, Freud put forward various schemas of development that dictated our personality and variations in our behaviours, such as conforming to social norms. The agents at work within these drives and the accompanying stages of development were commonly referred to as defence mechanisms. Defence mechanisms were put forward as being ways in which the subject could cope with the real and disturbing psychological issues that they had to face throughout life, such as anxiety and confusion. These mechanisms consisted of such concepts as denial, projection and regression and are commonly established psychological phenomena that infor the core rationale of developmental and psycho-dynamic paradigms (Freud, 1917/1973). Although these factors are well established concepts within mainstream psychology, they still depend upon a structural paradigm to be understood. Much criticism has come in the form of humanistic approaches who have suggested that these models of development are dependent upon the objectifying of the subject and that this approach is a convenient theoretical model rather than being scientifically accurate. Another school of thought is one that actually rejects objective science at its core. The phenomenological approach to psychological study is primarily based upon perception and subjectivity. Formed as a way of countering the empirical approach to psychology that had led to the field of cognitive psychology, phenomenological psychology suggested that knowledge was learned entirely from the external environment via lessons that were encapsulated in our experience (Merleau-Ponty, 1964). Detaching from the scientific notion of tabula rasa, which had dominated the opposing stance to the rationality of science, Merleau-Ponty looked at the notion of perception and in particular how it was informed by phenomena, rather than through observation of objects taken from their natural environment. Fundamental to this approach is the notion that everything we experience accords to the phenomena in which it is presented, and so objective science cannot tell us about our psychological experience. Th is approach most ertainly rejects psychology, as well as many other enquiries, as a scientific pursuit. We can see from these schools of thought that to call psychology a pursuit of objective scientific fact is flawed. However, we can also see that there is a strong emphasis in each case placed upon validity. Even the rejection of objectively defined scientific principles shown by the phenomenological approach gives indication that validity and limitation of enquiry are paramount, which is surely the premise of scientific analysis. Bibliography Asch, S, E., (1956) Studies of independence and conformity. Psychology Monologues, 70. Baron, R, S., Vandello, J, A., Brunsman, B. (1996) The Forgotten Variable in Conformity Research. Journal of Personality and Social Psychology. 70. Bruner, J, S., Goodnow, J, J., and Austin, G, A., (1956) A Study of Thinking New York: John Wiley and Sons. Chomsky, N., and Fodor, J, A., (1980) Statement of the Paradox, in Piatelli Palmarini, M. (ed.). Freud, S., (1917/1973) Introductory lecture on Psychoanalysis. Harmondsworth; Penguin. Merleau-Ponty (1964) The Primacy of Perception London: Routledge Miell, D., Phoenix, A. and Thomas, K. (2002) Mapping Psychology 1. Milton Keynes, Open University. Sherif, M., (1936) The Psychology of Social Norms. New Yoprk: Harper. Skinner, B, F., (1946/1990) Walden Two London: Collier Macmillan. Cell membrane: Structure and purpose Cell membrane: Structure and purpose BIOPHYSICAL CHEMISTRY ESSAY: CELL MEMBRANE STRUCTURE AND PURPOSE Introduction Cell membrane is a biological barrier that separates the interior part of the cell (i.e. the Cytoplasm, nuclei and the other cell organelle) from the outer environment, thus permits cellular individuality and also gives shape to the cell. This membrane is a mixture of lipids, protein and carbohydrates, therefore is a complex structure. The membrane is semi-permeable and thus only allows selective ions and molecules to go through it into the cell or leave the cell. This is achieved by formation of concentration gradient across the membrane, which many biological processes depend upon. The movement of the biological molecules across the membrane is either passive, which happens without the input of cellular energy or active transport that requires the cell to use energy. The cell membrane also helps in maintaining cell potential. Proteins of the cell membrane form the essential component of the biological membrane since they function as pores, channels or transporters. Proteins thus have the capability of selective passage across the lipid bilayer. Some proteins that are embedded in the cell membrane act as molecular signals and therefore carry out communication. They act as receptors and receive signals from other cells or from the external environment and elicit a response in the cell. Some proteins function as markers which aid in identification of unknown cells. The membrane also aids in intercellular interactions. The lipid bilayer of the cell membrane is only a few nanometres thick and is not permeable to most molecules that are soluble in water, and hence acts as a barrier to regulate the transport of ions, proteins and other molecules through the membrane. Since the phospholipid bilayer is not permeable to many ions, it helps in the regulation of salt concentration and pH by regulating the pumping of ions in and out of the cell via proteins called ion channel pumps. The Fluid mosaic model is the most widely accepted biological membrane model that was proposed in the year 1972 by Singer and Nicolson. Floating in the phospholipid bilayer are molecules of protein, which is analogous to icebergs floating in a sea. The model is referred to as fluid because of the lateral motion of the bilayer macromolecules, and is referred to as mosaic because of the different molecular components [1][2][3][4]. Purpose of cell membrane Cell membrane performs the following functions: Membrane Transport of Small Molecules: Transport proteins present in the bilayer can transport polar molecules through the membrane. There are various types of membrane transport proteins: Uniport This simply moves the solute from one side to the other side of the membrane. Cotransport This system moves two solutes simultaneously across the lipid bilayer. They are two types of this transport-symport (solutes are sent in the same direction) and antiport (solutes are passed in opposite directions). These transports are come under the category of passive transport where no energy expenditure is involved. Here the solute moves from a higher concentration to a lower concentration gradient. Examples of this include channel proteins, which allow the solute to pass if they are of a specific charge or size. Carrier proteins bind to the solute and help in its movement through the bilayer.[5] There are two main categories of transport of molecules are there in cells: Active transport Passive transport Small molecules like oxygen, ethanol and carbon dioxide pass through the membrane by simple diffusion (passive transport) down a concentration gradient. Transport of macromolecules like proteins, polynucleotides and polysaccharides is done by active transport using ATP, against the concentration gradient. There are two types of active transport : 1) Exocytosis Process by which waste substances are removed from the cell by vesicle formation and expulsion [6]. 2) Endocytosis- The molecule causes the cell membrane to bulge inward, thus forming a vesicle. Phagocytosis is a type of endocytosis where the whole cell is engulfed. Pinocytosis is another type when the external fluid is engulfed. Receptor-mediated endocytosis occurs when the material to be transported binds to specific molecules in the membrane. Example: transport of insulin and cholesterol into animal cells [6]. Cell signalling across the membrane Transmembrane signalling occurs through the generation of a number of signals like cyclic nucleotides, calcium, phosphoinositides and diacylglycerol. Specific signals of neurotransmitters hormones and immunoglobulins bind to the specific receptors on the membrane, which are mostly integral membrane proteins. This is the Ca2+-phosphatidylinositol signalling pathway which plays a major role in transmembrane signalling in a large number of different cell types. This pathway leads to the activation of G-proteins. This initiates activation of phospholipase C and the subsequent formation of DAG and IP3 which triggers the generation of repetitive [Ca2+] spikes [7]. Intercellular intractions Gap junctions are structures that allow the small molecules that are up to ~ 1200 Da to be transported from one cells cytoplasm to the other. These structures contain proteins called connexins. Six connexins form a hemiconnexin and two hemiconnexins form a connexon. These connexions in the gap junction form cylindrical bridges through which substances are transported between cells [1][8]. The Fluid mosaic Model: This model is the widely accepted membrane model. The membrane has a biomolecular lipid bilayer layer. There are proteins that are inserted in it or bound to the surface. Integral membrane protein is the proteins that are embedded in the membrane they play a key role as transporters for various molecules that cannot enter through the cell membrane. The integral proteins have an extra-cellular domain and cytoplasmic domain and are separated by a non-polar region that holds it tightly in the membrane. Proteins that are loosely bound to the to the outer membrane are called the peripheral proteins. Many of the proteins that are present and almost all the glycolipids have an externally oligosaccharides chains that are exposed outside the membrane [1][9]. The membrane fluidity very much depends on the lipids concentration in the membrane. The hydrophobic chains of the fatty acids are much aligned therefore giving it a stiff structure. The transition(Tm) is the temperature at which the transition takes place from ordered to disordered state, this is the change that happens in the hydrophobic side chain. Cholesterol affects the fluidity of the membrane. It increases fluidity below Tm and decreases fluidity above Tm. Modifications to the fluid mosaic model state that the lipids and proteins in the membrane are not randomly distributed. Randomness occurs when interaction energy of these molecules are close to their thermal energies. Since interaction energies cannot be in a narrow range due to large number of interactions, there is very less chance for randomness to occur. Hence the model was found to be more mosaic than fluid [10]. The modified view of membrane model is shown in figure 7[10]. Specialised structures in the membrane: There are some special features in the membrane like lipid rafts, caveolae, tight junction, desmososmes, adherens junctions and microvilli. These are found in the recent years of research. Lipids Raft is the area in the membrane that has relatively higher concentration of cholesterol, sphingo-lipids and some proteins, than the other parts of the membrane. It plays a major role in cell signal transduction. This is under research that if we increase the amount of this and clustering them closely may increase the overall efficiency of the cell. Caveolae are special types of lipid rafts. Many of them have protein called caveolin-1 that is involved in the process. They were observed under electron microscope and were found to be flask-shaped. Proteins that are detected in this also play a role in signal transduction, example is insulin. Proteins found in this also play in role in folate receptor. This field is a growing interest for research. Tight Junctions are present on the surface of the membrane and their major function is to prevent diffusion of macromolecules between cells. They are present below the apical surface of the epithelial cells. They are made up of various proteins including occludin, various claudins and junctional adhesion molecules [1]. Desmosomes also called macula adherens are the specialised cell structures for cell to cell adhesion. Their function is to resist shearing force. They are mostly found in simple and stratified squamous epithelium [11]. Adherens junctions are the proteins that usually occur at cell- cell junction .They are made up of proteins like cadherins, ÃŽÂ ²-catenin, ÃŽÂ ±-catenin and sometimes delta catenin. Their function is to provide strong adhesion between adjacent cells. They hold the cardiac muscle cells firmly together as the heart beats and do not allow it to collapse [12]. Microvilli are very small finger like structures found on the cell membrane. They are mainly found on the epithelial cells, they increase the surface area of the cells therefore increasing the absorptive capacity of the cells. Actin filament extends from the end of these microvilli [13]. Components of cell membrane Cell membrane is a complex structure and is composed of proteins, carbohydrates and lipids. Different cell membranes have different compositions. Lipids Phospholipids: There are two major class of phospholipids out of which in the cell membrane the phosphoglycerides are the most commonly found ones. Phospholglycerides are esters that are made up of two fatty acids, phosphoric acid and a trifunctional alcohol. Phosphoglycerides with sphingomyelin have Sphingosine backbone instead of glycerol. They play a role in signal transduction. They are prominent in myelin sheaths [1]. Glycosphingolipids: These are sugar containing lipids that are present in the membrane. They have a backbone made of ceramides. These are amphipathic molecules consisting of a ceramide lipid anchor linked to an oligosaccharide chain of variable length and composition [1]. They are required for proper functioning of nervous system. Determining their function will help to understand neurodegenerative disorders, cancer, immune function and diseases of metabolism [14]. STEROLS The most import sterol in the membrane is cholesterol. Proteins in cell membrane Integral membrane proteins: also called intrinsic proteins t has its some part of the protein embedded in the phospholipid bilayer. Most of these proteins have hydrophobic side chains that interact with membrane phospholipids fatty acyl groups. They are called transmembrane proteins if they one or more membrane spanning domains. The transmembrane proteins of the membrane spanning domains are made up of ÃŽÂ ± helices or multiple ÃŽÂ ² strands [8]. These proteins are made up of two hydrophilic and one hydrobhobic region. The hydrophobic region traverses through the bilayer. They are asymmetric in nature. The transmembrane region of many integral membrane proteins is made up of a bundle of hydrophobic ÃŽÂ ±-helices [7]. Their major role is as transporters, and are also structural membrane-anchoring domains. They function by transporting hydrophilic molecules through the membrane. Many Integral Proteins Contain Multiple Transmembrane ÃŽÂ ± lpha Helices [8]. Examples: Insulin receptor, Glycophorin, Rhodopsin, CD36 and GPR30. Peripheral membrane proteins: They are also called as extrinsic proteins; they do not interact with hydrophobic core of the membrane phospholipid bilayer. They are bound to the membrane by interaction with the intergral proteins or are bound to the bilayer outer lipids polar heads groups. They are only present in the cytosolic region of the cell membrane. They play an important role in signal transduction. Some peripheral proteins are localized to the surface of the plasma membrane, these are called exoplasmic proteins. Peripheral enzymes are involved in the synthesis of different membrane components like lipids , cell wall oligosaccharides , or proteins. Membrane peripheral proteins are of five types: Structural proteins, channel proteins, transport or carrier proteins, enzymes and receptor proteins. Carbohydrates: Carbohydrates are attached to membrane lipids and proteins as short oligosaccharide chains. Proteins attached with sugar molecules are called glycoproteins and lipids attached with sugar molecules are called glycolipids. The carbohydrates form a protective coat called glycocalyx around the cell, which helps in cell recognition. Glycoprotein Glycoproteins are formed by glycosylation of proteins. There are two types: N-glycosylation (sugar links to nitrogen atom of asparagines residue) and O-glycosylation (sugar attaches to hydroxyl group of serine or threonine rsidues). Examples of glycoproteins found in the body are mucins, collagens, transferrins, immunogloulins, etc. Glycolipids Glycolipids are lipids linked to oligosaccharide chains. Examples include glycosphingolipids which contain a hydrophobic ceramide, N-acylsphingosine and saccharides. They are generally located on the outer membrane surface. The composition of the carbohydrate chain depends on the type of the cell and development of the organism.[9] Refrences: [1] Harper [2] http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellMembranes.html [3] http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookCELL2.html [4] http://www2.estrellamountain.edu/faculty/farabee/biobk/biobooktransp.html [5] http://library.thinkquest.org/C004535/cell_membranes.html [6] http://library.thinkquest.org/C004535/molecule_transport.html [7] Chay, Lee, Fan, 1995 Appearance of Phase-locked Wenchbach-like Rhythms, Devils Staircase and Universality in Intracellular Calcium Spikes in Non-excitable Cell Models [9] The Fluid Mosaic Model of the Structure of Cell Membranes Cell membranes are viewed as two-dimensional solutions of oriented globular proteins and lipids. S. J. Singer and Garth L. Nicolson [10] http://www.cytochemistry.net/cell-biology/membrane3.htm [11] http://en.wikipedia.org/wiki/Desmosome [12] http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/J/Junctions.html [13] Krause J. William (July 2005). KrauseHYPERLINK http://books.google.com/books?id=cRayoldYrcUCpg=PA37HYPERLINK http://books.google.com/books?id=cRayoldYrcUCpg=PA37s Essential Human Histology for Medical Students. Universal-Publishers. pp. 37-. ISBN 9781581124682. Retrieved 25 November 2010. [14] ] Glycosphingolipid functions: insights from engineered mouse models, doi: 10.1098/rstb.2003.1268 Phil. Trans. R. Soc. Lond. B 2003 358, 879-883 [15] [16] Endosytosis image: http://php.med.unsw.edu.au/cellbiology/index.php?title=2009_Lecture_6 excoystoisis http://cellbiology.med.unsw.edu.au/units/science/lecture0805.htm figure 1 Gap junction pic: http://www.cytochemistry.net/cell-biology/membrane3.htm cell membrane pic http://www.microscopy.fsu.edu/cells/plasmamembrane/plasmamembrane.html