Biological Rhythms

Biological rhythms are the regular fluctuations in our bodily processes and in consciousness over time. Many of these fluctuations occur over a course of a single day and are therefore known as circadian rhythms (from the Latin words “around” and “day”).

Most people are aware of their fluctuations in energy level, alertness and mood over the course of a day, and research findings indicate that such shifts are closely related to the changes in underlying bodily processes. In addition, the circadian rhythms seem to shift with age; as people grow older, their peeks often tend to occur earlier in the day. These cyclic changes in our bodily processes –are related to task performance. In general, people do their best work when body temperature and other internal processes are at or near their personal peaks.

SUPRACHIASMTIC NUCLEUS (SCN): This structure located in the hypothalamus, also known as a biological clock, plays a major role in the circadian rhythms. It appears that individual cells in this structure tick-or in other words keep track of time. This biological clock responds to light. Morning resets our biological clock, synchronizing it with the external world. This is necessary or else our clock seems to operate in a 25 hour cycle; thus if it were not reset each day, our internal biological rhythms would get farther and farther out of synch with the world around us.

PINEAL GLAND: For long term biological rhythms, such as mating season and hibernation another structure in the mid brain, the pineal gland, seems to play an important role. This gland which sits on he top of the mid brain, just in front of the cerebellum, secretes a hormone known as melatonin. It’s connected to SCN and secretes melatonin in response to input by SCN.

Melatonin influences several structures in brain, regulating the production of hormones, affecting many basic physiological processes. It is secreted mostly at night; so when nights are long, larger amounts are secreted. High levels of melatonin seem to trigger hibernation in many species. When days get longer, lower level of melatonin gets many species to enter into their summer phase or spring phase; they become more active and begin to seek a mate.

Maslow’s Hierarchy of Needs

Abraham Maslow proposed a hierarchy of needs to account for the range of human motivation. The base level in the hierarchy of needs is the physiological needs, pertaining to thirst, hunger, sleep and other drives necessary to the maintenance of life. Their needs must be adequately satisfied before higher ones can be considered.

If these requirements are reasonably satisfied, then the motivation for safety emerges, such as the needs for security, protection and freedom from danger.

If the physiological and safety needs are satisfied, the individual move up to another position in hierarchy, in which the psychological or social motives begin. At this point we find the motivation for love and belongingness, which includes having friends, a family, sexual relationship and membership in a group.

When the motivation for love and belongingness is achieved the individual is prompted to still another level, called self-esteem. It includes achievement, competence, approval, recognition, prestige status, etc.

Maslow was extremely interested in the highest level of his hierarchy, which he called self actualization. It is the fulfillment of our unique potentials. According to Maslow and other humanistic psychologists, it is the self initiated stirring to become what one is capable of being; the motive for, reaching ones full potential, for expressing ones unique capabilities. Self actualization which comes under the category of Meta needs.

META NEEDS

In  Abraham Maslows theory of personality, meta needs are the higher human needs which include justice, beauty, honor, order and self actualization. Metaneeds cannot be dealt with, according to the theory, until the pro-potent needs are fulfilled.

Ø  Wholeness(unity)

Ø  Perfection(harmony)

Ø  Completion(ending)

Ø  Justice(fairness)

Ø  Uniqueness(individuality)

Ø  Autonomy(self sufficiency)

THE EXTRA SENSORY PERCEPTION –“THE SIXTH SENSE”

Extrasensory perception—ESP—is defined by parapsychologists as the acquisition by a human or animal mind of information that could not have received by normal, sensory means. Some researchers, however, take issue with the term "extrasensory perception." They protest that the phenomena may not be "perception" at all, as the receiver of this information does not know if the knowledge is right or wrong when he or she first perceives it. It takes a corroborating incident to convince anyone that he or she has perceived anything via extrasensory means. Some parapsychologists prefer to say "paranormal cognition," but this term is subject to the same sort of criticism if the receiver is not instantly certain of the validity of the information. Besides, the researchers insist that the material in their field will eventually merge with present-day physics, so the adjective "paranormal" may be considered a misnomer.

Contrary to common usage, a parapsychologist is not a psychic, a mentalist, an astrologer, or one who gives psychic readings. A parapsychologist is generally a member of the Parapsychological Association, which was founded in 1957 and elected an affiliate of the American Association for the Advancement of Science in 1969. A parapsychologist is a scientist who is seriously interested in the paranormal (or anomalous phenomena), which includes telepathy, clairvoyance, precognition, psychokinesis, hauntings, reincarnation, and out-of-body or near-death experiences.

*Bruce Willis and Haley Joel Osment in the film "The Sixth Sense"

Here are brief definitions of the areas of ESP that are studied by parapsychologists:

Clairvoyance is the awareness, without physical aids or normal sensory means, of what is going on elsewhere. In recent years, clairvoyance has sometimes been called remote viewing.

Out-of-body experience (also called astral projection) is the apparent projection of the mind from the body, often with the seeming ability to travel great distances in a matter of seconds.

Precognition (premonition) is the obtaining of information about the future that could not have been gained through normal means.

Psychokinesis (telekinesis) is the ability of movement of objects, seemingly caused by some force unknown to physical science. The direct action of mind on matter is the parapsychologists' current nominee as the energy involved in poltergeist cases—those bizarre occurrences when bottles and crockery float through the air, fires break out on living room tables, or disembodied voices cackle threats and obscenities.

Telepathy is the ability of transference of thought from one mind to another. Distance and time seem unable to affect this phenomenon.

Even from these brief definitions, it becomes apparent that many attributes of parapsychological, or psi, phenomena overlap. It has long been a contention of serious parapsychologists that each of these types of phenomena is but a single aspect of the life and the universe of which humans are a part. If such parascientific phenomena as the projection of the astral self, the ability to glimpse the future, and the facility to convey telepathic impressions are established, the boundaries of humankind's universe become limitless.

_______________________

*AP/WIDE WORLD PHOTOS

COGNITIVE PERSPECTIVE IN PSYCHOLOGY

The word cognition refers to perception of world around us, some aspects of learning, memory, and comprehension of our social environment. In other words, cognition refers to the processing of information that we receive through the senses. Such processing is the basis of the experience we have, which we call mind. Differences in the ways we process information may lead to differences in behaviour. According to cognitive perspective, humans can best be characterized as information processing organisms. In seeking to understand why people behave as they do, the processes that are most relevant to examine are how people take in information through their senses and how they process it to yield any behaviour. Learning and storage in memory of what is learned provide the basis of thinking. But how learning progresses may reflect innate human tendencies interacting with a given environment.

FIGURE GROUND PERCEPTION: PSYCHOLOGICAL EXPLANATION

Perception is the organizing process by which we interpret our sensory input. According to this principle, a figure is perceived in relationship to its background. The perception of the object or figure in terms of colour, size, shape, intensity and interpretation etc. depends upon the figure ground relationships. Figure ground organization is probably inborn, since it is the first perceptual ability to appear after cataract patients regain sight. Even 5-month old babies respond to figure-ground patterns. In normal figure-ground perception, only one figure is seen. In reversible figures, however, figure and ground can be switched. According to Gestalt psychologists, a number of factors influence the perception of a figure. Some of them are

1. Nearness: Stimuli that are near each other tend to be grouped together.

2. Similarity: Stimuli that are similar in size, shape, colour, or form tend to be grouped together.

3. Continuation: Perception tend toward simplicity and continuity.

4. Closure: the tendency to complete a figure, so that it has a consistent overall form.

Apart from these, learning and past experience greatly influence the perception of figure.

PSYCHOLOGY: INDIAN AND GREEK PHILOSOPHICAL BACKGROUND

One of the first stones laid for the foundation of scientific psychology when an ancient Greek physician Alcmaeon (BC 700), put forward the proposition that mental life is a function of brain.

The greatest scholar of ancient Greek, Aristotle, considered heart as an organ responsible for spiritual processes. Aristotle was the first to give the systematic exposition of psychological concepts on his discourse “on the soul”. Socrates compared his own vies with those of his predecessors, analyzing and evaluating them in detail. His discourses regarding this may be seen as the first psychological enquiries. He talked about the unity of the soul and body, which was entirely controversial to the view points of his master Plato. Plato was one of the preliminary proponents of dualism, which explained that soul and body are two separate entities.

The ancient Indian thoughts too supported heart as the principal organ of mental activity, the cardiocentric view. In India, the most influential documents were Vedas. It is generally agreed that Vedas reach their culmination in the ‘Upanishads’. ‘Vedantas’ take further the objective idealistic trend already present in ‘Upanishads’. All these are currently identified as the part of Hindu philosophy. Synopsizing these collections of philosophical doctrines, the self was not the mortal body, but a special intuitive consciousness in which the external and internal were not distinguished. This was given the name ‘Atman’, which is identical with Brahmin – the boundless cosmic consciousness, the base of the world. The individual soul or the soul of one human being is not ‘Atman’. Its divine nature is obscured by the constant stream of sensory perceptions and bodily urges. Only through the knowledge and strict moral discipline can the soul be become free and thereby be identified with the ‘Brahman’.

Apart from Hinduism, Jainism and Buddhism got developed and flourished in ancient India. Jainism considered that soul was locked in the body, and therefore, unfree. Buddhism did not agree with the existence of a soul as a separate entity. According to Buddhism, mental-spiritual life is a stream, of never repeated moments, of different states, following one upon another.

Yoga, another school of thought, suggested the control of all the mental activity, which darkens knowledge, in order to attain true knowledge. Yoga elaborated a system of techniques which can be practiced regularly to make this a reality. It included eight fold way and begins with regulation of mental functions, attention and thought.

There are some other schools too, such as, Sankhya, Purva Meemamsa, Nyaya, Vaisheshika etc. These schools also dealt soul as a subordinate aspect of their prime concern with metaphysics and ethics.

SCHOOLS OF PSYCHOLOGY: STRUCTURALISM

Psychology’s first major theoretical position or school came from the writings of Wilhelm Wundt, a professor of philosophy, who founded the first formal laboratory of Psychology at the University of Leipzig, in Germany, in 1879. Wundt’s laboratory was the site of formal research conducted by many students such as Tichener, Weber etc., who became some of the most renounced psychologists in the world. According to Wundt, the subject matter of psychology was immediate conscious experience. The mind is the sum total of various mental experiences (thoughts, feelings, sensation, attention etc.) and consciousness is the total sum of the mental experiences. Psychologists thus should seek to understand the structure of the mind. Therefore, the school came to be known as structuralism. The structuralists hoped to develop a sort of “mental chemistry” by analyzing experience into basic “elements” or “building blocks”.


To study the elements of the mind Wundt developed “introspection method” – a method in which trained individuals report in detail on their conscious experiences in response to specific stimuli (e.g., sounds, optical illusions, other visual stimuli) that are presented to them under controlled conditions. Wundt’s studies led him to conclude that there are three basic elements; which he called sensations (the direct products of external stimulation), images (sensation like experience produced by the mind), and feelings (the emotional component of an experience).

PHILOSOPHICAL ORIGINS OF PSYCHOLOGY

How we behave and why we behave so are questions that have aroused curiosity from time immemorial. In the earliest period of the history of psychology, they were answered quite unscientifically, merely on the basis of superstitions and speculations as follows:

It was believed that a person’s behaviour was the result of his fate which was bound to be influenced by the movements of the planet. In case we know the position of planets at any particular moment, we could tell and predict the behaviour of the person by evaluating his horoscope. Besides the role of planets, demons, spirits, ghosts and other supernatural forces were also held responsible for varying human actions. In this way, the cause and forms of human behaviour were being located in something outside the human being.

The Greek philosophers are credited to look inside the human beings for clues to behaviour. Socrates believed that inquiry into the nature of the cosmos is futile. As a result, he tried to adopt a question answer method of peeping into the nature of man. Plato drew a sharp distinction between mind and body, assigning the former by far the key role for generating behaviour. Aristotle’s concept of the soul proved a corner stone in Psychology for centuries. He viewed the ‘soul’ or the ‘psyche’ meaning ‘life’ and considered the mind as a living moving phenomenon that directs the activities of the body. However, he considered mind and body as united and thus brought Psychology into the realm of Biology.

Roman Stoics and Epicureans contributed to the development of Psychology in ways that paralleled the fate of natural sciences in Rome. Both these philosophies were limited in scope and were expressed mainly in Roman religious practices. They did not follow the Greek attempts to devise a comprehensive system of human knowledge. Rather, they formulated somewhat general attitudes towards life. However, the psychological implications of these views were limited.

In the discussion regarding the philosophical origins, the thoughts formulated in India cannot be kept isolated. Much of the knowledge of ancient India comes from the Vedas, the Book of Knowledge. The Vedas are a collection of lessons, hymns, poetry and prose that were compiled from oral recitations. The Hindu philosophies have important implications regarding psychology. According to the Hindu philosophy, the individual is characteristically a part of a greater and more desirable unity. Individual growth is away from individuality and toward an emergence into the bliss of universal knowledge. This assertion of individuality is seen not as meaningful in itself, but rather as an activity to be minimized and avoided. Sensory and mental events are unreliable. Truth lies in transcending sensory and mental activities and voiding consciousness. In short, the integrity of the individual person is questionable, because the individual occupies an insignificant place relative to the entire, harmonious complexity that is the cosmos. The Hindu philosophy seems to have an extreme coincidence with the humanistic view and the centrality of the individual self, which has been expressed in the west recently.

Buddhist philosophy is another deeply influenced one, which became very popular in China, Japan and South-East Asia, but founded by the Indian Philosopher and Teacher, Siddhartha or Gouthama Buddha (563-483 BC). Buddha’s preaching sounds almost behaviouristic and materialistic. It guided the followers to strive, through ascetic self-discipline and careful training, to attain the happiness of annihilating individual consciousness. Again the importance is given to move beyond individuality, as it is in the Hindu philosophy.

Origins of Psychology

The term psychology was coined in the sixteenth century from the Greek word “psych” which means “mind” or “soul” and “logos” means “study”. The initial meaning of Psychology was thus, “the study of the soul”, and in the earlier period Psychology was the branch of Philosophy. By late 19th century, when Psychology emerged as a science, it had become the “science of mind”. Beginning in the second decade of the twentieth century, many psychologists abandoned the study of mind in favour of the study of behaviour. Consequently, by 1920, Psychology became “the scientific study of behaviour”. However, by 1960s, there was a revival of interest in studying the mind. Thus it became, “the science of behaviour and mental processes”.

The philosophical Roots of Psychology:

This can be traced back to more than 2000 years ago, when Buddha and Confucius focused on the powers and origin of ideas. In other parts of the world, Socrates, his student Plato and Plato’s student Aristotle pondered whether mind and body are connected or distinct. These ancient philosophers set the stage for the development of the science of Psychology through their reliance on observation as a mean of knowing about people.

It is during seventeenth century, philosophers introduced the idea of dualism – the world is divided into two elements (here, mind and matter). The mind accounted for our thoughts and feelings, Matter referred to our physical being, our bodies. Mind and matter were believed to be completely independent of each other. Mind was believed to be the part of God’s domain. Therefore, it was only studied by theologians, while matter was studied by other scholars in universities.

In contrast there were other philosophers who suggested that mind can influence body and body can influence mind. This view is known as Interactionism.

Rene Descartes, a French philosopher suggested that there was a link between mind and body, and perceptions. He said that mind and body interact through the Pineal gland, which is found deep within the brain. His approach to understand human behaviour was based on the assumption that the mind and body influence each other to create a person’s experience.

Toward the end of seventeenth century, the British Philosopher John Locke contributed yet another important concept to the foundation for modern psychology. He said that infants come to this world with blank minds, with no experience (tabula rasa or blank tablet). Later, whatever experiences a person has in life are written into this blank tablet. Knowledge, thus, is the result of a building up of experiences.

The Scientific Roots of Psychology:

By the nineteenth century, scientists were making progress in answering questions about the nature of Psychological processes that Philosophers are having difficult with. One such remarkable name was of Johannes Muller who described how electrical signals were conducted by nerves within the body.

Herman Von Helmholtz, a German Physiologist, showed how receptors in the eyes and ears receive and interpret sensations from the outside world. Gustav Fechner demonstrated that our perceptions of physical stimuli like the loudness of a sound or brightness of a light are related in lawful, predictable ways to the physical energies of these stimuli. He used the technique called Psychophysics to quantify the relationship between physical stimulation and mental experiences.

Psychology as we know it today was born in a laboratory in Germany in the late 1800s, when Wilhelm Wundt ran the first true experiments in psychology’s first lab. By 1879, he founded the first formal laboratory for research in psychology at the University of Leipzig. Because of this and many other contributions, Wundt is described as the founder of experimental psychology. Alexander Bain, another philosopher founded the influential journal Mind in 1876. G. Stanley Hall took psychology to America. He founded the first laboratory of psychology at Johns Hopkins in 1883. He started the American Psychology Association in 1892 and then became its first president.

Piaget's Theory of Cognitive Development

Jean Piaget(august 9,1980), a professor of psychology at the university of Geneva from 1929 to 1954 was a swiss developmental psychologist who is most well known for organizing cognitive development in to a series of stages. Piaget's theories of psychological development have proved influential. Among others, the philosopher and social theorist Jurgen Habermas has incorporated them into his work, most notabily in the Theory of Communicative Action.

Piaget's theory of cognitive development is a stage theory – a type of theory suggesting that all human beings move through an orderly and predictable series of changes. According to Piaget, children are active thinkers who are constantly trying to construct more accurate or advanced understanding of the world around them. In other words, from this perspective, children construct their knowledge of the world by interacting with it. Children build such knowledge through two basic processes – assimilation and accommodation. Assimilation involves modifying one’s environment so that it fits into one’s already developed ways of thinking and acting. Accommodation involves modifying oneself so as to fit in with existing characteristics of the environment. In general, children will try for equilibration – the tendency of the developing individual to stay “in balance” intellectually, by filling in gaps in knowledge and by restructuring beliefs, when they fail to test out against reality.

The first stage of cognitive development lasts from birth until somewhere between eighteen and twenty-four months. During this period, termed the sensorimotor stage, infants gradually learn that there is a relationship between their actions and the external world.

Sometime between the age of eighteen and twenty-four months, toddlers acquire the ability to form mental images of objects and events. At the same time, language develops to point at which they begin to think in terms of verbal symbols-word. Thinking is limited to immediate sensory experiences and motor behaviours. It is a trial-and error type of thinking. Infants know objects only in terms of their direct action upon the objects. Thus, a nipple is something to be sucked and so forth. The infant functions according to the principle “out of sight, out of mind”. This is because, infants are incapable of mentally constructing symbol or represent the object that is no longer visible.

Piaget's second stage – the preoperational stage – extends from two to seven years. During this stage, children become increasingly capable of symbol formation. E.g. 4 year old child uses cigar box to represent a cart etc. Other symbol systems used by children at this time include language, gesturing, mental imagery and representational drawing. Reasoning in this stage is neither inductive nor deductive, but transductive (from particular to the particular). Egocentrism, inability to take the point of view of another person, will be evident. Pre-operational children assume that others see the world just as they themselves see it. This is not selfishness, but an intellectual limitation.

The third stage – concrete operational stage – extends from seven to twelve years. In this phase, children’s thinking is limited by their reliance on what can observe in tangible. They may understand the abstract concepts such as democracy. Decentration, or the child’s ability to shift his/her attention from one perceptual attribute to another, becomes generalized and applicable during this period. Reversibility, child’s ability to mentally retrace his or her actions or thoughts (think backward), is understood. Conservation, the ability to understand the physical properties remain same so long as noting has been added or taken away, skills develop. Children in this age will be able to appreciate jokes. Concrete operational thinker is able to define a class and list all members (classification ability) of the class. There will be a loss of egocentrism.

The final stage of cognitive development, during which individuals may acquire the capability for deductive or propositional reasoning is called Formal operations. During this period, major features of adult thought make their appearance. The adolescent become capable of several forms of logical thoughts.

All the theories in psychology are subjected to careful scientific testing, but grand theories such as piaget's require especially careful assessment, because they are so sweeping in nature. Piaget’s theory is highly insightful in many ways-but that, like virtually every theory, it should be revised in the light of new evidence.

What is psychology?

Psychology is memory, stress, therapy, love, persuasion, hypnosis, perception, death, conformity, creativity, learning, personality, aging, intelligence, sexuality, emotion and many, many other topics (Coon, 1999).


Psychology

Psyche = Mind;

Logos = Knowledge or study.

A Working Definition

Psychology is the science of human and animal behaviour (Coon, 1999; Morgan et al, 1986). It includes the application of science to human problems (Morgan et al, 1986).

The above definition indicates that Psychology is a science. A science is a body of systematic knowledge that is gathered by carefully observing and measuring events. It studies about human and animal behaviour. Behaviour is anything we do – eating, sleeping, talking, thinking, dreaming, gambling, taking drugs, watching TV, learning Spanish, basket weaving, reading, sneezing etc. Behaviour can be classified into covert and overt. Psychologists are interested in both visible behaviour and hidden mental events.

Much of the overt behaviour can be studied by direct observation.

E.g.: Running will help a person move faster than walking.

But to study about the internal events, other precise measuring tools have to be used.

E.g.: Depth of a person’s happiness or sadness cannot be measured by mere observation.

Measurement in Psychology is often more difficult than it is in sciences such as physics and chemistry because many of the things psychologists study cannot be measured directly by physical scales. However, not everything in Psychology is so difficult to measure. For example, it is easy to count the number of times a person behave in one way in one situation, and another way in another situation.

The definition also indicates that Psychology has an applied side. It can be used to solve “real-life” problems. Basically, even though the area of application varies, the importance goes to find working solutions to the problems and to apply it.

Empiricism

Psychologists try to be objective in their observation. Therefore, they have a special respect for empirical evidence, information gained from direct observation and measurement. Whenever possible, psychologists settle disputes by collecting data (observed facts) that can be verified by two or more independent observers. The observations are systematic. It is also a young science. However, some of the observations are very difficult in Psychology. Due to ethical and practical concerns, many of the questions are still unanswered.

Goals of Psychology

The goals of Psychology are to describe, understand, predict and control behaviour. Describing behaviour means to make a detailed record of behaviour. Understanding denotes to state the causes of behaviour. Prediction is the accurate of forecast of behaviour. Prediction is especially important in psychometrics, a specialty that focuses on mental measurement, such as personality and intelligence testing. Control means altering the conditions that influence behaviour in predictable ways.

The ultimate goal of Psychology is to accumulate information to help humanity (Kimble, 1989).

References:

Coon, D (1999), Introduction to Psychology: Exploration and Application, 6th ed., West Publishing Company.

Morgan, C. T.; King, R. A.; Weisz, J.R. & Schopler, J (1993), Introduction to Psychology, Tata McGraw-Hill Edition.

Subliminal Perception

Perception of a stimulus presented below the threshold for conscious recognition is called subliminal perception. Subliminal means below the normal limen or threshold or limit. An experiment done on the college students can be taken as an illustration for subliminal perception. A set of college students was shown a cartoon character flashed on a screen. The cartoon was paired with photographs of faces expressing joy or disgust. The faces were flashed at a speed that made them undetectable. Since the students have not previously seen the cartoon character, they were forming a first impression. Apparently, the students chose more negative terms to describe the cartoon character that had been paired with a disgusted face.

Many firms have tried subliminal method of advertisements. In one such attempt, the words “Eat popcorn and Drink Coca-cola” were flashed in theatre screens for 1/3000 second every 5 seconds during movies. In the period of 6 weeks the messages ran, the firm claimed an increase of 57.5 percent in popcorn sales and an 18.1 percent increase in Coca-cola sales. However well-controlled experiments have shown that subliminal stimuli are basically weak stimuli. More over, subliminal advertisements have proved largely ineffective. Even so, advertisers still use subliminal messages

SIGNAL DETECTION THEORY in Psychology.

Signal Detection theorystates that the perception of sensory stimuli involves the interaction of physical, biological and psychological factors. The intensity of the signal, the degree to which the signal can be distinguished form background noise and the psychological factors like motivation, expectations and learning together will determine the perception.

The intensity of the stimuli is just one of the factors that determine whether people will perceive sensory stimuli or a difference between two signals. Another is the degree to which the signal can be distinguished from background noise. It is easier to hear a friend in a quiet room than in one where people are clinking silverware and glasses and engaging in competining conversations. The quality of a person's bilogical sensory system is still another factor. Here we are concenred with the sharpness or acuteness of the individual's sensory system. We consider whether sensory capacity is fully developed in diminished because of illness or advanced years.

Signal detection theory also considers psychological factors such as motivation, expectations and learning. One psychological factor in signal detection is focusing or narrowing of attention to signals the person deems important.

Signal detection theory emphasizes the psychological aspects of detecting and responding to signals. The relationship between a physical stimulus and sensory response is more than mechanical or mathematical. Training, learning, motivation and many other psychological states such as fatigue or alertness influences the detection of signals to a large extent.

Psychology as a Science

Psychology, like other sciences, seeks to describe, explain, predict and control the events it studies. Psychology thus seeks to describe, explain, predict, and control behaviour and mental processes.
Psychological theories are based on assumptions about behaviour and mental processes, contain statements about the principles and laws that may govern them and allow us to derive explanations and predictions. Many psychological theories combine statements about behaviour (such as eating or aggression), mental processes (such as attitudes and mental images), and anatomical structures or biological processes. For instance, many of our responses to drugs such as alcohol and marijuana can be measured as overt behaviour, and they are presumed to reflect the biochemical actions of these drugs and our (mental) expectations about their effects.
A satisfactory psychological theory allows us to predict behaviour and mental processes. For instance, a satisfactory theory of hunger will allow us to predict when people will or will not eat. A broadly satisfying comprehensive theory should have a wide range of applicability. A broad theory of hunger might apply to human beings and lower animals, to normal-weight and over-weight people, and to people who have been deprived of food for differing lengths of time. If our observations cannot be adequately explained by, or predicted from a given theory, we should consider revising or replacing that theory.
In psychology, many theories have been found to be incapable of explaining or predicting new observations. As a result, they have been discarded or revised. For example, the theory that hunger results from stomach contractions may be partially correct for normal-weight individuals, but it is inadequate as an explanation for feelings of hunger among the overweight. Contemporary theories focus also on biological variables and situational variables.
The notion of controlling behaviour and mental processes is controversial. Some people erroneously think that psychologists seek ways to make people do their bidding--like puppets on strings. This is not so. Psychologists are committed to a belief in the dignity of human beings, and human dignity demands that people be free to make their own decisions and choose their own behaviour. Psychologists are learning more all the time about the various influences on human behaviour, but they implement this knowledge only upon request and in order to help an individual or organization.