An experimental reexamination of the theory of the neural quantum in the sensory discrimination of pitch and loudness

102 Pages·05.956 MB·English

by  Corso, John Fiermonte

AH EOTRMEHTAL RS*mJtIHATI6N OF THE THEORY
OF THE KSURAL QUANTUM IN THE SENSORY
DISCRIMINATION OF FITCH AHD LOUDNESS
by
John Flermonte Corso
A dissertation submitted In partial fulfillment of the
requirements for the degree of Doctor
of Philosophy, in the Department of Psychology
in th© Graduate College of the State
University of Iowa
June 1950
ProQuest Number: 10598587
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the writer wishes to express his
sine^re&t appreciation to Professor
Bon Lewis for suggesting the problem
and offering critical guidance through­
out the course of the study,
.Further aeknowledgssent Is mad© to
Hr, H* H, Burfthardt for the design of
the electronic circuits used in the
©xperimental apparc.tus,
11
TABLE OF COMTira
Gimp tor page
1 Theoretical background %
Introduction* . . . . . * 1
The classical theory of
discrimination . ........ . 1
The theory of the mural quantum* * 7
XI Statement of the problem.............. 33
XII Experimental procedure............... 34
Subjects* . , . . .......... ♦ . 3^
Apparatus . . . . . . . . . . . . . 35
Loudness discrimination. . . . 35
Pitch discrimination . . . . . 46
Additional devices . . . . . . 4?
Procedure » ......... 49
Pitch discrimination . . . . . 50
Loudness discrimination* . . . 52
Levels of certainty* . . . . . 52
IV Results . . . . . . . . . . . . . . . . 54
Pitch discrimination....... 55
Loudness discrimination. . . . 60
Levels of certainty* . . . . . 67
V Discussion of results. . . . . . . . . . 69
71 Summary and conclusions. . . . . . . . . 74
Appendix A . . . . . . . . . . . . . . * 77
Appendix B . . . . . . . . . . . . . . . 76
Appendix 0 . . . ............ 80
Appendix D ♦ . . . ............ 86
Appendix E . . . . . . . . . . . . . . . 91
Bibliography . . . . . . . 93
ill
TABLE OF FI0UBE3
Figur© pag©
1. Th© psychometric function - two categories
of Judgment ......... * 3
2* Boring’s chart of th© psychometric function
for the two-point threshold . . . . . . . . . 6
3. A schematic representation of th© basic
notions involved in the theory Of the neural
quantum ........... . . . . . . . . . . . . 14
4* Th© distribution of surpluses and th©
probability function ............. IS
5# The fora of the psychometric function in the
sensory discrimination of pitch and loudness
according to the theory of the neural quantum 24
6. Block diagram of the apparatus required to
provide tonal stimulation in the Investigation
of loudness discrimination . • . ....... 36
7* Circuit-diagram of the band-pass filters used
to eliminate transient frequencies in pitch
and loudness discrimination . . . . . . . . . 3$
8. Frequency selectivity curves for the filters
used in loudness discrimination ......... 40
9. Block diagram of the apparatus required to
^ provide tonal stimulation in the investigation
of pitch discrimination ♦ . , . . ......... 43
10. Frequency selectivity curves for the filters
used In pitch discrimination . . . . . . . . 48
11. Representative non-linear psychometric
functions obtained in pitch discrimination » 59
12. Representative linear psychometric
functions obtained in pitch discrimination • /6l
-IV
TABLE OF FIGURES
(Oontlnued)
Figure page
13* Representative non-linear psychometric?
functions obtained in loudness discrimination' 64
14, The two linear psychometric functions
obtained In loudness discrimination * * , „ * 65
15* Psychometric functions obtained in pitch
discrimination for two trained observers
under a low and under a high certainty
criterion * * .......... .... 68
TABLE OF TABLES
Table page
X Chi*square values obtained 1b pitch
discrimination 56
It Ratio values for the linear functions
obtained In pitch discrimination * . ♦ „ . * # 57
III Ghl*square value® obtained In loudness
discrimination ......... 62
IV Ratio values for the linear functions
obtained In loudness discrimination « . « * . 66
V Total scores- on Seashore tests • * * » « . . * 77
VI Observer R* B» * * * . * ............. .. „ . 80
VII Observer R* R* . • • . . . • ♦ - . .......... 80
VIII Observer £»K» « • * « * • * * * « « * » * • » 81
IX Observer F* ?......... 81
X Observer 82
XI Observer W« 82
XII Observer R* S* . * * . * . • • • » • • * < *. • 83
XIII Observer K. K. * * 83
XIV Observer J* B« * , • . . « . * .. * * • * * * 84
Observer S. S.........* » * , * 84
XV
XVI Observer K* H* B* 85
XVII Observer Jo F* C, 85
XVIII Observer G* V. ♦ ........... 86
XXX Observer f* S.............. 86
vi
TABLE OF TABLES
(Continued)
Table Pag®
XX. Observer A. 3. • §7
XXI Observer M. R, . . ............. 87
XXII Observer J. C. . . . . . . ................ 88
XXIII Observer If. w. . . . . . . ........... 88
XXIV Observer J. S. . . . . . . . . . . . . . . . . 89
XXV Observer L. S, . . . . . .......... 89
XXVI observer H. 0. . . . . . . . . . . . . . . . . 90
XXVII Observer K. 8. . . . . . . . . . . . . . . . . 90
Til
1
Chapter I
THEORETICAL BAOECrROUOT
Introduction
the discriminatory ability of th© human organism
in audition may b© considered from two points of view:
first, the ability to perceive the presence, or absence, of
a given auditory stimulus under specified conditions and,
second, the ability to detect a change in a given auditory
stimulus whenever one of its attributes is Increased or de­
creased In physical magnitude. The basic concepts Involved
In these two aspects of discrimination are the absolute
threshold and the differential threshold, respectively (22),
The present study utilises the concept of the differential
threshold as an approach to the theoretical formulations
which have been advanced to account for the behavior ob­
served under conditions of pitch and loudness discrimina­
tion, The first of these formulations is called the classi­
cal theory of discrimination; the second, and more recent
formulation, the theory of the neural quantum,
The Classical Theory of Biscrimination
The classical view of sensory discrimination may
be introduced through the determination of the differential
threshold, or difference Ilmen. This threshold is defined
as the smallest stimulus difference which can b© perceived
an observer a specified proportion of th© times pres­
ented, Since the method of right and wrong oases Is gen­
erally regarded as the most satisfactory psychophysical
procedure for determining threshold values (5)* this
method will now be presented in detail.
At the beginning of a di aer 1mlna 11 on
the several values of the variable stimulus to be
are carefully selected, These stimuli., some greater and
some less than th© standard in physical magnitude, are
presented to- the subject a large number of times in an
irregular order, or in a prearranged order uhimown to th©
subject. On each trial the variable is preceded, accomp­
anied, or followed by the standard.* The subject makes a
judgment of 'rtgreater** or nlessn with reference either to the
standard or to the variable, or In accordance with -some pre­
arranged plan. In the calculation of the differential thresh­
old values, the proportion of each of th© two types of
judgments is determined for each value of the variable
stimulus- used, The results can be presented graphically in
the form of a psychometric function {21) as shown in Fig, 1,
Hi© upper differential threshold Is conventionally
defined as the distance between th© standard stimulus {Rs}
and the variable stimulus (By.) for which the psychometric
curve has an ordinate of p = 0,75* This is th© increment
which must b© added to th© standard stimulus in order for