My teacher has given me a couple of articles that I need to read. I have already started and I have five more. What he wants me to do is read these articles (in English) and then include the key points on the power point. What he wants me to include is:- Information on the subjects (very general like the amount, gender, age) and the tests/questionnaires used.- Protocol- Results- Conclusion- LimitationsThe subjects of these articles are on migraines. However, the slides need to be written in french. when i assign the paper i will attache two examples of what is being asked of me. For the 6th slide, I am supposed to circle the element that are used to explain the reason for the migraine. If there is no explanation, then you can leave question marks.Below i have attached the articles choose one and write the slides according to the instructions above. Provide a high quality work

Summary Discomfort glare conditions were generated in an experimental
viewing cubicle supplied with a variable luminance glare source operated by a
manually controlled dimmer. Repeated settings of the four IES discomfort glare
criteria were made by forty-one volunteer subjects all of whom were recruited
from three different industries and a wide range of employment categories. At the
end of twenty days of practice large differences in the settings were found between
subjects for each glare criterion and certain differences emerged between each of
the three groups. This wide variation is consistent with other studies on sensory
discomfort. It is concluded that many different factors are likely to be the cause
of such variability and that further research into them is required in order to
understand why people are sensitive to glare and other aspects of the physical
environment.
and group differences in discomfort glare
Individual
responses
P. T. STONE,
BSc., ABPsS., FIllumES and S. D. P. HARKER, BA, MSc
The aim of this paper is to draw attention to variation among people in their responses to discomfort
glare. Hopkinson- demonstrated that wide observer
differences exist and showed2 that suitable individual
variability after they were
making glare judgements. His
published material mainly centres around the consistent observers and elaboration of his findings on
observer variance, especially for large area sources,
is so far unpublished.
The data presented here were obtained during an
experimental programme to determine the effects
of age on discomfort glare response. This necessitated giving all the subjects repeated glare presentations to make them ‘experienced’ observers during
which individual differences in sensitivity emerged.
The authors believe that the extensive variability
obtained in such observations should be widely
appreciated, especially in view of the trend towards
higher lighting levels which may generate glaring
conditions for many more people than is presumed
from present knowledge.
subjects
reduced their
given experience
in
Method
A caravan served
and housed all the
convenient mobile laboratory
experimental equipment. Three
firms kindly supported the study by allocating space
for the caravan by allowing members of their
staffs to act as subjects during the course of the
working day. The subjects were a small mixed
sample of the working population, with an age range
from 20 to 65 years and including such employment
categories as semi-skilled and skilled factory
workers, office workers, management and research
as a
workers.
Apparatus
Glare assessments
were
made within the
caravan
seated at a cubicle which was equipped
variable luminance glare source together
background lighting. The sources used for
generating the glare consisted of 24, 2 ft 40 W ’Daylight’ fluorescent tubes over-run at 80 watts on a
thyristor circuit dimming to extinction. The dimmer
control required several turns to produce a small
change in luminance; it was hoped that this would
overcome any effect of artificial consistency induced
by easy and rapid setting of the control.
by subjects
with
with
a
The glare source exposed to the subject consisted
of a rectangular acrylic screen, (35. 6 cm x 30. 5 cm,
w = O. 16 steradian) illuminated by the above lamps
assembled in a white painted semi-cylindrical casing.
An even luminance was obtained across the screen
surface which was found to give 4U UOtJ cd/m ? at
maximum intensity.
The background luminance provided by eight, 20 W,
2 ft ’Daylight’ fluorescent tubes mounted in the ceiling
of the cubicle was held constant throughout the
experiment at 200 cd~’m~. These lamps were shielded
from the subject’s view by baffles. Both source and
background lighting were supplied with power via
a stabiliser and changes in intensity could be brought
about independently in the source and in the background if required. In order to monitor the intensity
of light at the source, a photocell attached to a digital
voltmeter was mounted on a sloping surface facing
the opal screen thus permitting a rapid reading of all
settings. The principal features of the apparatus
are illustrated in Fig. 1.
Direct measurements of the source luminances were
made and calibrated against the voltage readings on
the digital voltmeter. All the measurements subsequently obtained in the experiment were recorded
as voltages and checks on the reliability of the conversion were carried out.
41
~’ag.1. The glare
cubicle and side elevation to show eye
Calculation of the
glare constantt
increasing the source
The effect of
luminance was
to change the inter-reflection within the cubicle and
thereby increase the background luminance above
the standard. At maximum source output the background luminance was raised to 425 cd/m2. It was
necessary to take this change of background luminance into account when calculating the glare constant
and a correction has been made in all of the results
for such changes.
An important consideration in the calculation of a
glare constant is the source displacement from the
line of sight. In theory and in many actual situations
the glare source is treated as a point source and
therefore it is easy to determine the angle of displacement and the position index. In this apparatus
the source area could not in any sense be treated as
a point and two methods of taking this into account
were considered. One was to use the droop diagram
published by Petherbridge and Longmore3. However,
this yielded such a small glare constant at the lower
settings that on conversion to the glare index a
numerical result of less than 4anity was obtained.
Expressing the just perceptible level in terms of
an index less than 2. ~ seemed meaningless and did
not appear from the experimenters’ experience to
represent the subjects’ performance adequately.
Therefore, an alternative approach was taken. The
angular displacement from the line of sight to the
lower edge of the glare source was used as the basis
for ~.11 calculations of the position index.
The source area was chosen on grounds of experimental expediency to fit the housing of the fluorescent tubes and to generate the maximum glare
possible. In terms of previous studies4 it falls somewhere between a small and a large area source.
Some thought was given to its treatment as a large
area source but in view of its indeterminate position
42
position,
source
and
background lighting.
and the lack of certain
guidance from the literature
glare constant
the standard formula for the
.8
1
1.6. ~~y0
G Bs
– x-
Bb 1.0
p1.6
employed in all calculations and converted
10 iog~~~ to obtain the glare index. The correction for increased background luminance discussed
earlier is not a correction for a large area source.
was
by
It is realised by the authors that the values of the
glare index shown in the results may not completely
align themselves with the IES glare index values
because of the various experimental conditions discussed above. The objective of this paper is to describe variability and not to validate the glare index
system; the subject’s responses could have been
expressed in luminance or in voltage but the glare
index was the more appropriate form of description
as it bought about a greater linearity to the data than
the other scale units.
It is worth remembering that Hopkinson points out
in a discussion5 on large area glare sources ’that
the peripheral visual field has a considerable influence
on the discomfort sensation’. Our method of calculating th~ ~~s3tics~ index may therefore give values
which are not unreasonably removed from the basic
glare levels used in practice because of the attempt
to take account of the area of the source in the
peripheral field.
The
subjects
The
subjects were initially recruited by a manager
personnel officer from each firm. From those
who volunteered to take part a final selection was
or
made on the basis of a number of criteria. The
most critical test adopted was a sheet of Weston
on grey paper with
contrast of 0.64 and subtending a 3’ gap at the
reading distance employed. Each subject had to
show that he or she could detect the gaps. The other
criteria were equal age and sex representation but
it was difficult to be rigid about these as the total
numbers available in each firm were not large and
as can be seen in Table 1 an imbalance between the
ratio of males and females occurred in Group I.
the term ’distracting’ being substituted for ’acceptable’. It was felt that it would be
more consistent with the other instructions to employ
a term which was appropriate to the setting of a level
which is ’just greater’ than the changeover point.
Although the visual acuity test acted as a criterion
for selection, it was thought worthwhile to make
assessments of the general visual capacity of each
subject. Three additional tests were adopted, but
minor anomalies did not exclude subjects provided
they were successful in the Landolt ring test. The
~Ilcst uncomfortable ~Za~e ’B’: The point at which
the subject finds the source sufficiently glaring to
cause distress and annoyance if work has to be
carried out in the location over a considerable period
of time. A level such that the subject would take
steps to improve his condition before continuing with
his work.
complex Landolt rings, printed
a
additional assessments used
(1)
(2)
follows:
The Master Vision Screener to obtain fourteen
quick chacks on aspects of distance and near
vision for acuity, phoria and stereopsis.
The Ishihara colour
possibility
(3)
were as
plates
of gross colour
to establish the
deficiency.
Perimetry, to measure the extent of the visual
field in the 90° and 180° meridians and to ensure
there were no gross defects in the central visual
field.
subjects made up as shown in Table
successfully completed the full trial period. The
group number given in Roman numerals refers
A total of 41
1
henceforth to the individual firms.
Table 1. Distribution of
subjects
in the three groups
slightly amended,
Hopkinson and Petherbridge2 define ’just acceptable
glare’ as the changeover point between ’acceptable’
and ’distracting’ glare.
Just intolerable glare ’A’: The most intense sensation of glare, which would be sufficient to demand
immediate attention in a working situation, even if the
workplace was in use for only a very short period.
Not to be taken as a level where physical incapacity
is necessarily produced.
These four levels were described to all the subjects
the first, second and third days and repeated if
requested, at a later stage.
on
It
emphasised throughout that judgements made
the individual could not be wrong and that provided the settings were made on the basis of the
subject’s own feelings the task was being correctly
performed. It was further suggested that the subjects should always think in terms of a working environment and the necessity of pursuing some visual
ta.sk. The majority of subjects attended the caravan
at a fixed time every day. In some cases, conflicting
demands made such a routine impossible and those
subjects came when it was convenient.
was
by
Experimental procedure
It is important to note that only two subjects out of
the total sample were professionally connected with
lighting research or design, the rest being occupationally naive with respect to special experience or
knowledge of lighting.
Instructions t~a
subjects
The subjects were required to judge the glare in
terms of the four well-known criterion steps established by Hopkinson6. Each subject was instructed
that he should report when the luminance of the
glare source reached a point at which it produced
a sensation corresponding to one of the following
specified levels.
perceptible glc~~e ¢f~’; The point at which the
aware of the glare source as a patch of
light, without suffering any distress from it.
Just
subject is
distracting glare ’C’: The point at which the
subject feels that the glare source is irritating,
perhaps drawing the gaze toward it, but causing no
Just
great annoyance. The title used for this level
was
Every subject made eight settings of each glare
level daily, i.e. a total of 32 settings per day, occupying about fifteen minutes when the routine was
established. The first day, however, was used as an
instruction period and is not included in the results
and the second day was used for further practice.
On arrival inside the caravan the subject was allowed
several minites to adapt to the prevailing level of
illuminance in the cubicle. Two different procedures
were used relating to the operation of the dimming
control and to the order of presentation of glare
levels. Group I were submitted to one set of procedures, and both Groups II and III to the other set.
An important part of our objective was to find d1scomfort glare levels which could be considered more
closely to represent an individual’s true sensitivity
after repeated practice. After Group I had completed
their sessions it was thought that the time required
to reach a consistent level might be accelerated for
other groups by a small change in the procedure.
Furthermore, it seemed that a different psychophysical method was desirable. No attempt was made
to formulate an experimental design by which any
differences in procedures could be systematically
investigated as these changes had not been contemart the beginning of the trials. They were made
43
for convenience and no major differences were
anticipated. The details of the procedures are given
below.
Table 3.
groups
Summary
of
experimental schedules for all
GROUP I
All 14 subjects made their settings by starting from
no glare and then setting level D, followed by level C,
then B and finally level A. When that sequence was
completed, the source luminance was riased to a
point above the previously set level of A and a descending series in the order of A, B, C, D was completed. This approach was used up to and including
day 8. From the ninth day until the end of the trial,
a slight modification was introduced by asking the
subject to make a setting from a base level of ’no
glare’ and returning to that level before setting the
next level, but still maintaining the ascending sequence. On the descending series, the base point
was some arbitrary level above the previously set
’just intolerable’ level. This schedule is summarised
in Table 2.
Table 2. Order c~f presentation c~f glare
settings for the ascending and descending
series
Results
The total experimental programme included studies
the performance of a visual task under conditions
of glare but this work is not reported here. Only
the sensitization of subjects is described and the
topics selected for consideration are:
on
(a)
(b}
(a)
The experimenter maintained control of the dimmer,
which was adjusted in accordance with the subject’s
command throughout the trials.
GROUPS II AND III
With these 27 subjects the previous sequence of
settings was abandoned as it was thought that a
systematic bias might have been introduced by giving
all the glare levels in a direct sequence.
A
new
schedule
was
substituted in which all the 24
possible orderings of the A, B, C, D glare levels were
set. The subject was assigned different orders at
random and it took three days to exhaust all the
orders. This new arrangement operated from day 3
to day 2~g a period that effectively breaks down into
six three-day cycles. All of the individual settings
were from a ’no glare* base.
An additional change was introduced after the eighth
day when two three-day cycles had been completed.
The dimming control for the glare source was given
directly to the subjects, whereas up to that point the
experimenter had operated it. The latter made
adjustments at as constant a rate as possible but this
was less controllable when the subjects performed
the action for themselves.
A summary of the different
is given as follows:
44
experimental procedures
the influence of the different procedures on the
sensitization of the subjects to discomfort glare,
and
~ variability among the subjects, the topic of
central interest to this report.
Effect of different procedures
An initial tendency to become
more sensitive with
is displayed by all three groups up to the
end of the second three-day cycle, and Group I maintained this level of sensitivity for the rest of the
trial, as shown in Fig. 2. The values plotted in Figs.
2, 3 and 4 are the mean of the settings for each of
the three days in a cycle, an analysis which brings
out the trend rather more clearly.
practice
When Groups 3~ and m are inspected (Figs. 3 and 4)
it can be seen that from the second 3-day cycle
onwards, a trend completely opposite to that of
Group I emerged. The changes presented by Group I
are consistent with the findings of Hopkinson and
Petherbridge7 and with the experience of lighting
specialists in general. This was the result expected
for ai.i groups and the changes in Groups H and III
were totally unexpected. It will be noted that this
reversal of the trend in Groups II III occurred
after the dimming control had been given to the
subjects to operate for themselves. The majority of
subjects demonstrated these marked trend changes
but some of them tended to maintain, with minor
oscillations, a flat trend, especially those who set
their four glare levels close together. One person
in Group II showed a trend similar to the subjects
in Group I, (see Fig. 6)…
Figures 5, 6, 7 and 8 are day-by-day analyses of the
sensitivity curves of four subjects who have been
Fug. 2. Means discomfort glare settings each
cycle, Group I.
selected to illustrate
some
of the characteristic
patterns found. These figures portray the results
from this experiment more readily than any other
method of expressing the data, excepting that the
most extreme subjects are not represented. The
graphs clearly show three features: (a) the difference
in trend in the glare index with experience of making
settings; (b) the difference in spacing between the
glare levels; (c) a great variety in levels for any one
glare
criterion.
(b)
Variability of the final day setting
It was hoped that the extensive period devoted to
these trials would make the subjects ’experienced’
observers, or at least make them more sensitive
in discriminating glare levels and reduce variability
due to lack of previous experience. Groups I and III
show a levelling off of the curves and Group II shows
at least a diminished rate of change on the last
cycle. It certainly seems reasonable to suggest that
Groups I and III had achieved stability and that
Group II was probably not far off this.
An analysis made of the average of the settings for
each of the glare levels set on the twentieth day by
every subject is presented in Table 4 showing measures of central tendency and dispersion.
Before deriving this data, the mean of each subject’s
eight settings was calculated and Table 4 is based
on the averaging of these means for all subjects.
This is therefore the most economical expression
Fi~. 3.
As
Fig. 2 Group
Il.
of the total variation, making for a simpler illustration of the relation between subjects but minimising
the variance of each individual.
Variation is usually described either by the standard
deviation or variance, but as some data from the
final day settings showed a tendency towards skewness (as assessed by Yule’s procedures8) other descriptions of variation not dependent on normality of
distribution are given. The simplest of these is the
total range which has as its limits the smallest and
largest settings for the group. Another measure is
the interquartile range which shows limits of the
glare index set by that 50% of the group which lay
between the bottom 25% and top 25/. of the total
range.
9
The median is the value which divides the range in
such a way that 50Q of th …
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