3. Experimental Psychology
• Experimental psychology is the scientific study of behavior, motives, or
cognition in a laboratory or other controlled setting in order to predict,
explain, or influence behavior or other psychological phenomena.
• Experimental psychology aims at establishing quantified relationships and
explanatory theory through the analysis of responses under various
controlled conditions and the synthesis of adequate theoretical accounts
from the results of these observations.
• It is an approach to psychology that treats it as one of the natural sciences,
and therefore assumes that it is susceptible to the experimental method.
4. Experimental Psychology
• Experimental psychology features at least three central components that
define it
• Empiricism: the collection of data that can support or refute a theory.
• Falsifiability: a foundational aspect of all contemporary scientific work.
• Determinism: the notion that any event has a cause before it.
7. Experimental Psychology
Historical Background
• 1874 - Wilhelm Wundt published the first experimental psychology textbook "Principles of Physiological Psychology".
• 1875 - William James opened a psychology lab in the United States. The lab was created for the purpose of class
demonstrations rather than to perform original experimental research.
• 1879 - The first experimental psychology lab was founded in Leipzig, Germany. Modern experimental psychology dates
back to the establishment of the very first psychology lab by pioneering psychologist Wilhelm Wundt during the late
nineteenth century.
• 1883 - G. Stanley Hall opened the first experimental psychology lab in the United States at John Hopkins University.
• 1885 - Herman Ebbinghaus published his famous "On Memory", which was later translated to English as "Memory: A
Contribution to Experimental Psychology."
• 1887 - George Truball Ladd published his textbook "Elements of Physiological Psychology," the first American book to
include a significant amount of information on experimental psychology.
• 1887 - James McKeen Cattell established the world's third experimental psychology lab at the University of Pennsylvania.
• 1890 - William James published his classic textbook, "The Principles of Psychology."
8. Experimental Psychology
Historical Background
• 1891 - Mary Whiton Calkins established an experimental psychology lab at Wellesley College, becoming the first
woman to form a psychology lab.
• 1893 - G. Stanley Hall founded the American Psychological Association, the largest professional and scientific
organization of psychologists in the United States.
• 1920 - John B. Watson and Rosalie Rayner conducted their now-famous Little Albert Experiment, in which they
demonstrated that emotional reactions could be classically conditioned in people.
• 1929 - Edwin Boring's book "A History of Experimental Psychology" was published. Boring was an influential
experimental psychologist who was devoted to the use of experimental methods in psychology research.
• 1955 - Lee Cronbach published "Construct Validity in Psychological Tests," which popularized the use of construct
validity in psychological studies.
• 1958 - Harry Harlow published "The Nature of Love," which described his experiments with rhesus monkeys on
attachment and love.
• 1961 - Albert Bandura conducted his famous Bobo doll experiment, which demonstrated the effects of
observation on aggressive behavior.
9. Experimental Psychology
Contribution of Weber
• Ernst Heinrich Weber (1795-1878) was regarded as a predecessor of
experimental psychology and One of the founders of Psychophysics, the
branch of psychology that studies the relations between physical stimuli and
mental states.
• Weber experimentally determined the accuracy of tactile sensations, namely,
the distance between two points on the skin, in which a person can perceive
two separate touches.
• In 1834 he conducted research on the lifting of weights. From his researches,
he discovered that the experience of differences in the intensity of sensations
depends on percentage differences in the stimuli rather than absolute
differences. This is known as the just-noticeable difference, difference
threshold, or limen.
10. Experimental Psychology
Contribution of Weber
• He formulated Weber’s law:
ΔI/I = k
• where I is the original intensity of stimulation,
• ΔI is the addition to it required for the difference to be perceived,
• k is a constant is known as Weber’s constant.
11. Experimental Psychology
Contribution of Fechner
• Gustav Theodor Fechner (1801-1887) postulated that mind and body,
though appearing to be separate entities, are different sides of one
reality.
• He also developed experimental procedures, still useful in experimental
psychology, for measuring sensations in relation to the physical
magnitude of stimuli.
• Fechner’s experimental method became the basis for experimental
psychology and later inspired Wilhelm Wundt, who created the first
scientific Psychological laboratory.
12. Experimental Psychology
Contribution of Fechner
• Fechner experimentally sought to confirm this insight by discovering close
quantitative relationships between conscious experience and physiological
stimulus, eventually discovering the law that the intensity of a sensation
increases as the log of the stimulus characterizes psychophysical relations.
(S = k log R)
• where S is the sensation,
• R is the stimulus.
• This law proved the existence of an evidence-based connection between body
and psyche. This formula was named the Fechner-Weber law because it is
based on the theory of the just-noticeable difference, advanced earlier by
Ernst Heinrich Weber.
13. Experimental Psychology
Contribution of Wundt
• Wilhelm Maximilian Wundt (1832-1920) made Psychology as an independent
field of study. He is one of the first and most famous originators of the
program of development of psychology as an independent science.
• Wundt is regarded as the founder of experimental psychology.
• He Introduced experimental method of investigating conscious processes as
well as the use of introspection into psychology.
• Founder of the first research psychologist laboratory (1879) at the University
of Leipzig.
• Founder of the first journal of psychology “Philosophical studies” (1881), from
1903 “Psychological studies”.
14. Experimental Psychology
Contribution of Wundt
• Wundt argued that psychology has its own laws:
a). the law of creative synthesis,
b). the mental relationships law,
c). the law of contrast,
d). heterogony of ends (purposes) (Heterogonie der Zwecke).
15. Experimental Psychology
Contribution of Galton
• Sir Francis Galton (1822 – 1911) was an English Victorian polymath,
anthropologist, eugenicist, tropical explorer, geographer, inventor,
meteorologist, proto-geneticist, psychometrician, and statistician.
• Galton produced over 340 papers and books throughout his lifetime and was
knighted in 1909.
• He created the statistical concepts of regression and correlation and
discovered regression toward the mean, was the first to apply statistical
methods to the study of human differences and heredity,
• He introduced the use of questionnaires and surveys for collecting data on
human communities, which he needed for genealogical and biographical works
and for his anthropometric studies.
16. Experimental Psychology
Contribution of Galton
• He was a pioneer in eugenics, coining the term "eugenics" and the
phrase "nature versus nurture".
• As an investigator of the human mind, he founded psychometrics (the
science of measuring mental faculties) and differential psychology (the
branch of psychology that concerns itself with psychological differences
between people, rather than on common traits).
18. Sensation
• Sensation is the process of acquiring sensory information from the
receptors and converting it into action potential.
• Every moment are sensory receptors receive large amount of
input which is scrutinized by attention processes.
• The information that is attended to is sent to the brain through
the neural network and the brain then begins to give meaning to
it
19. Sensation Process
• Stimulus: any object or event that elicits a sensory or behavioral response.
• Receptor process begins with the physical changes around the organism.
• Transduction: the conversion of one energy into another.
• Conversion of physical energy into neural impulse.
• Conduction: the channelizing of nerve impulses in the cortex through
several fibers.
• Efferent Code: nerve impulses reaching the destination in the form of
organized pattern of spikes.
20. Visual sensation
• The sensory experience which brings into awareness objects in the
environment through the act of seeing is referred to as vision or visual
sensation.
• The sense organ concerned with this is the human eye.
• The stimuli for visual sensation are the light rays.
21.
22. Structure of Eye
• Cornea: the transparent circular part of the front of the eyeball.
• Iris: regulates the amount of light that enters your eye.
• Pupil: the circular opening in the centre of the iris through which light passes into
the lens of the eye.
• Lens: a transparent structure situated behind your pupil.
• Sclera: the white part of the eye, a tough covering with which the cornea forms
the external protective coat of the eye.
• Choroid: the middle layer of the eye between the retina and the sclera. It also
contains a pigment that absorbs excess light so preventing blurring of vision.
• Ciliary body: the part of the eye that connects the choroid to the iris.
• Retina: a light sensitive layer that lines the interior of the eye. It is composed of
light sensitive cells known as rods and cones.
23. Structure of Eye
• Fovea: forms a small indentation at the centre of the macula and is the area
with the greatest concentration of cone cells.
• Rod cells are one of the two types of light-sensitive cells in the retina of the
eye.
• Cone cells function best in bright light and are essential for acute vision
• Optic disc: the visible portion of the optic nerve, also found on the retina.
The optic disc identifies the start of the optic nerve where messages from
cone and rod cells leave the eye via nerve fibers to the optic centre of the
brain. This area is also known as the 'blind spot’.
• Optic nerve: leaves the eye at the optic disc and transfers all the visual
information to the brain.
24. Visual Sensation
• Accessory structures of the eye are those that are not directly related the
sense of vision but facilitate the physiology of the eyeballs.
• Eyebrows – to shade the eyes from sunlight and to prevent perspiration from
reaching the eyes.
• Eyelids- to protect the eyes from foreign objects (e.g. dust particles) ,and to prevent
desiccation (drying) of the eyes by lubricating fluid.
• Conjunctiva- a mucous membrane on the inner lining of eyelids, which produces
lubricating and cleansing fluid for the surface of eye.
25. Visual Sensation
• Lachrymal gland- exocrine gland that
secretes a dilute saline solution called
tears for moistening the eyes. [Tears
contain mucus, antibodies ,and
antibacterial enzymes that protect the eye
from infections. Emotional tears also
contain enzymes that seem to help reduce
stress levels].
26. Auditory Sensation
• The auditory sensation or the sensation of hearing is next in importance
only to visual sensations.
• The major dimensions are duration, pitch, loudness and timbre.
• Different sounds last for different durations.
• Some sounds are heard for a short time and some for a long time, some
have a high pitch being very shrill like a scream while others have a low
pitch and are not shrill.
27.
28. Structure of Ear
• Outer ear consists of auricle and external auditory meatus and is
responsible for transferring sound waves from the environment to the
middle ear.
• Middle ear consists of the tympanic membrane and auditory ossicles. It is
responsible for amplifying sound waves into strong signals for the hearing
receptors to detect.
• Inner ear consists of cochlea, 3 semicircular canals, and the
vestibulocochlear nerves. inner ear is responsible for using
mechanoreceptors to detect stimuli for hearing and equilibrium and send
the nerve impulses through the vestibulocochlear nerve (nerve VIII) to the
brain
29. Auditory Sensation
• Auditory ossicles include the malleus, incus, and stapes, which are articulated to
one another, but not to the skeleton. The malleus is attached to the tympanic
membrane, stapes is attached to the cochlea.
• The middle ear also contains the eustachian tube (auditory tube) that connects
with the pharynx for equalizing air pressure in the skull.
• Sound waves hitting onto the tympanic membrane cause the auditory ossicles to
vibrate, resulting in amplification of the sound waves.
• When the ossicles vibrate waves in the endolymph fluid inside the cochlea are
generated.
• Endolymph waves bend the strerocilia (modified dendrites) of hearing receptors
called hair cells, which are located in the organ of corti on the basilar membrane.
• Bending of hair cells result in generation of nerve impulses which reach the
cerebrum via the cochlear nerve.
