Chapter 6 – german psychologists of the 19th & early 20th centuriesGerman Rivals to WundtWeber & FechnerErnst Weber (1795-1878)Just Noticeable Difference (JND)Gustav Fechner (1801-1887)Fechner’s ContributionRelationship of JND to StimulusFechner’s LegacyHermann Ebbinghaus (1850-1909)Early Academic CareerEbbinghaus ExperimentsEbbinghaus Forgetting CurveOther InvestigationsEbbinghaus’s ContributionsAn Applied ProblemFranz Brentano (1838-1917)Comparison to WundtBrentano’s Ideas About Mental ActsBrentano in PerspectiveCarl Stumpf (1848-1936)The Golden SectionStumpf’s Early WorkStumpf’s Tone PsychologyDebunking Sensational PhenomenaClever Hans & Von OstenStumpf’s Later YearsOswald Kulpe (1862-1915)Kulpe’s Experimental PsychologyThe “Wurzburg School”Investigations of Reaction TimeMore Wurzburg FindingsLost German PsychologistsCHAPTER 6 – GERMAN PSYCHOLOGISTS OF THE 19TH & EARLY 20TH CENTURIESDr. Nancy AlvaradoGerman Rivals to WundtErnst Weber & Gustav Fechner -- psychophysicistsHermann Ebbinghaus -- memoryFranz BrentanoCarl StumpfOswald KulpeWeber & FechnerErnst Weber (1795-1878)Weber published “De tactu” describing the minimum amount of tactile stimulation needed to experience a sensation of touch – the absolute threshold.Using weights he found that holding versus lifting them gave different results (due to muscles involved).He used a tactile compass to study how two-point discrimination varied across the body.On the fingertip .22 cm, on the lips .30 cm, on the back 4.06 cm.Aesthesiometric compassJust Noticeable Difference (JND)Weber studied how much a stimulus must change in order for a person to sense the change.How much heavier must a weight be in order for a person to notice that it is heavier?This amount is called the just noticeable difference JNDThe JND is not fixed but varies with the size of the weights being compared.JND can be expressed as a ratio: where R is stimulus magnitude and k is a constant and R means the change in R ( usually means change) kRRGustav Fechner (1801-1887)Fechner related the physical and psychological worlds using mathematics.Fechner (1860) said:“Psychophysics, already related to physics by name must on one hand be based on psychology, and [on] the other hand promises to give psychology a mathematical foundation.” (pp. 9-10)Fechner extended Weber’s work because it provided the right model for accomplishing this.Fechner’s ContributionFechner called Weber’s finding about the JND “Weber’s Law.”Fechner’s formula describes how the sensation is related to increases in stimulus size: where S is sensation, k is Weber’s constant and R is the magnitude of a stimulusThe larger the stimulus magnitude, the greater the amount of difference needed to produce a JND.He used catch trials to study guessing.RkS logRelationship of JND to Stimulus S.S. Stevens modified Fechner’s Log Law to a Power Function in the early 1950’s.http://en.wikipedia.org/wiki/Stevens%27_power_lawFechner’s LegacyHis methods are still used in psychophysics.Ideas from signal detection theory have been applied to a wide variety of other topics.Threshold for criminal behavior, scenic beauty.Scaling techniques, including rating scales, were placed on a sound scientific basis, especially by S.S. Stevens later work, continued by Luce & Narens.His speculations about split-brain studies were confirmed by Sperry.Hermann Ebbinghaus (1850-1909)Ebbinghaus was inspired by finding a copy of Fechner’s “Elements of Psychophysics.”He wanted to apply Fechner’s methods to study of higher mental processes.In 1877, he began developing procedures for studying memory.His major work, “Fundamentals of Psychology,” is dedicated to Fechner – “I owe everything to you.”Early Academic CareerEbbinghaus had no mentor to teach him techniques so he developed his own, highly original methods.He had no lab, no access to subjects, so he performed most experiments on himself.He followed rigorous experimental rules and spent 4 years replicating his first series of experiments.These were well received and widely recognized.His nonsense syllables were developed to avoid word familiarity, using a permutation formula.19 consonants, 11 vowels, 11 consonants = 2299Ebbinghaus ExperimentsFirst, he studied the relationship between the amount of material to be memorized and the time needed to learn it to complete mastery.His measure was number of repetitions needed.Second, he studied the effects of different amounts of learning on memory.His measure was savings – repetitions needed to relearn the original items after a delay.As repetitions increase, so does relearning time saved – overlearning helps.Ebbinghaus Forgetting CurveHis best known experiment studied the effects of passage of time on memory – his forgetting curve.In addition to graphing his data he developed a mathematical model by writing a logarithmic equation and deriving the parameters using the least squares method.He also compared means and variability and tested whether their differences exceeded chance.Other InvestigationsEbbinghaus studied the relative effects on memory of spaced versus massed practice, part versus whole, and active versus passive learning.Active, spaced learning was most effective.He found that meaningful material was much easier to learn and remember than material without meaning – Don Juan poem vs nonsense syllables.Lists learned before sleep were better retained.Ebbinghaus’s ContributionsThis was the first time a higher mental function had been studied experimentally.His book is “one of the most remarkable research achievements in the history of psychology” Roediger.His success established a paradigm for studying memory that was used for the next 90 years.An ecological approach later challenged this:Ulric Neisser challenged validity of lab tasks.Bahrick studied long-lasting memories.Banaji & Crowder defended lab-based studies.An Applied ProblemBreslau schools were concerned that children were too tired during an uninterrupted 8-1 school day.Griesbach tested mental fatigue and irritability using a two-point discrimination task.He proposed the day be broken into 2 short segments.Ebbinghaus disagreed because the measurement of sensory discrimination has little to do with mental