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SEJARAH PSIKOLOGIEKSPERIMENTAL

Week 3

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Ernst Weber (1795-1878)

Weber presented an extensive experimental

exploration of the sensory phenomenology of

tactile experienceCoining the phrase, just noticeable difference

(JND) to refer to the smallest perceptible

difference between two sensations that is

detectable by a human being or other animal.

Weber provided an existence proof for thepossibility of establishing quantitative

relationships between variations in physical

and mental events

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Gustav Fechner (1801-1887).

A pioneer in experimental psychology and

founder of psychophysics, the study of the

relationship between stimulus intensity andsubjective experience (detection) of the

stimulus

Psychophysicists usually employ experimental

stimuli that can be objectively measured,

such as pure tones varying in intensity, orlights varying in luminance. All the senses

have been studied: vision, hearing, touch,

taste, smell, and the sense of time.

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He popularized the Weber Law based on the study by ErnstWeber.

The most common use of psychophysics is in producing scales ofhuman experience of various aspects of physical stimuli. Forexample the physical stimulus of frequency of sound.

Frequency of a sound is measured in hertz, cycles per second.But human experience of the frequencies of sound is not thesame as the frequencies in hertz.

Doubling the frequency of a sound (e.g., from 100 Hz to 200 Hz)does not lead to a doubling of experience. The perceptualexperience of the frequency of sound is calledpitch

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Hermann von Helmholtz (1821-1894)

He viewed perception as requiring an

active, unconscious, automatic,

logical process on the part of the

perceiver which utilizes the

information provided by sensation

to infer the properties of external

objects and events.

Helmholtz anticipated much of later

top-down cognitive psychology.

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Helmholtz had also made another major contribution tophysiology. Stimulating nerves at various distances

from a muscle and measuring the time it took formuscular contraction, he estimated the rate of travelof the nervous impulse, and in the processincidentally introduced the technique of reaction-timeinto physiology and psychology

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Wilhelm Wundt (1832-1920)

Generally acknowledged as a founder of

experimental psychology and cognitive

psychology, and a student of Helmholtz.

Wrote Principles of Physiological Psychology

(1874). The Principles advanced a system of

psychology that sought to investigate the

immediate experiences of consciousness,including sensations, feelings, volitions (is

the study of will, choice, and decision)

apperception (perceive new experience in

relation to past experience) and ideas.

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In 1879 he took up a position atthe University of Leipzig, and

almost immediately set up thefirst two psychologicallaboratories in the world.

To Wundt psychology was thescience of experience andstudying psychologicalphenomenon therefore involvedstudying conscious experience.

This research took place in a smallclassroom that had earlier beenassigned to Wundt for use as astorage area.

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Wundt introduced Introspection

The researcher was to carefully observe some simple event -- onethat could be measured as to quality, intensity, or duration --and record his responses to variations of those events

Introspection is then a process that allows us to know our innerfunctioning through what we can gather about the functioning ofthe external world.

His greatest contribution was to show that psychology could be avalid experimental science. His influence in promotingpsychology as a science was enormous.

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Hermann Ebbinghaus (1850-1909)

Ebbinghauss systematic and careful approach tothe study of memory changed this paradigm bydemonstrating that higher cognitive processes

could also be studied scientifically. Themethodology he developed for doing thisbrought the study of memory out of philosophyand into the realm of empirical science.

Like his peers who used introspective

methodology, Ebbinghaus used his ownexperiences as a source of data. his approachto self-study was carefully controlled; theconditions of data collection followedprocedures that were commonly used inresearch in the so-called hard sciences

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To test his own memory, he first created 2300 nonsense syllables,each consisting of two consonants separated by a vowel (e.g.nog, baf). These syllables were necessary for a controlled

experiment because they were presumably free of anypreviously learned associations. He learned lists of thesesyllables until he had reached a pre-established criterion(perfect recall), and then recorded how many he was able toretain after specific time intervals. He also noted how manytrials were necessary for relearning after the syllables had been

forgotten.

His published the results inMemory: A contribution to experimental psychology(1885)

http://psychclassics.yorku.ca/Ebbinghaus/index.htmhttp://psychclassics.yorku.ca/Ebbinghaus/index.htm

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Meaningless stimuli are more difficult to memorize thanmeaningful stimuli (i.e. it is harder to memorize material that

does not have significance or relevance to the learner) His data revealed that increasing the amount of material to

be learned usually dramatically increases the amount of timeit takes to learn it. This is the learning curve.

Relearning is easier than initial learning, and that it takeslonger to forget material after each subsequent re-learning.

Learning is more effective when it is spaced out over timerather than crammed into a single marathon study session.

that forgetting happens most rapidly right after learningoccurs and slows down over time

His experiments demonstrated empirically

that