Running Head: EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
The Effects of Colour Term Acquisition on Categorical Colour Constancy
Candidate Number: 79015
University of Sussex
Word count: 5794
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Acknowledgements
I would like to thank Dr Anna Franklin and Dr Christoph Witzel for their much valued
support through the project. As my project supervisor Dr Franklin provided support and
opportunity wherever needed and provided the initial inspiration that drove my enthusiasm
for colour. Dr Franklin, Dr Witzel and I collaborated on the design of the experiment and Dr
Franklin and Dr Witzel provided feedback following the pilot. Dr Witzel also assisted with
some of the data collection, suggested some initial analyses and produced the figures not
possible with the usual programs. I would particularly like to thank Dr Witzel for the
weekend he spent learning carpentry to produce the frame used in each of the nurseries to
support the window filters. For the large part of data collection Ms Chen accompanied me, as
second experimenter, freely giving her time, for which I am also truly grateful. Stimuli,
remaining analyses and figures were independently produced.
Enormous thanks to the nurseries, their patient staff, kind parents of the child participants,
and of course to all the truly wonderful children who agreed to participate.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Abstract
Colour constancy occurs when a colour appears the same despite changes in illumination
which cause the light reaching the eye to be different. Few have studied the development of
colour constancy, in particular the impact that language has on categorical colour perception.
This study tested fourteen 36-51 month olds using a sorting task to sort 163 coloured stimuli
under four illuminant conditions. The consistency with which these were categorised was
analysed, showing that categorisation of colours was related to adult-like category maturity
and not to age. When illumination changes were considered, consistency again reflected
adult consistency, showing robust categorical colour constancy exists in children of this age
group. Results also showed that some colour categories were more stable than others, and
prototypical colours were named more consistently than those at the boundary of a colour
category. The findings from this study suggest that language may indeed influence
categorical colour constancy. It also suggests adult categories emerge from conceptual
linguistic categories which may in turn have their origins in the most perceptually stable
colours.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
The Effects of Colour Term Acquisition on Categorical Colour Constancy
Introduction
Colour constancy describes the way perception of surface colour remains the same,
despite alterations in illumination which alter the light reaching the eye. Without this, an
object that is blue outdoors in sunlight appears brown under typical indoor lighting, making
object identification rather difficult. On a day to day basis, we move from indoor
environments to outdoor environments, effortlessly maintaining a constant perception of the
colours we see, despite dramatic changes in the colour of illumination (Romero, HernandezAndre, Nieves, & Garcia, 2002) which in reality alter the spectrum of light reflected from the
surface, which finally reach the eye. The ability to bridge this gap between the message our
eye receives and our visual perception of colour is colour constancy.
Remarkably high levels of colour constancy can be found in adults. Most studies
suggest the visual system needs to discount the effects of any illuminants to calculate the
reflectance properties and therefore the colour of the surface in question (Foster, 2003;
Palmer, 1999). Various models have been proposed to account for colour constancy,
employing algorithms to estimate surface reflectance (Land, 1983, 1986), spatial averaging to
estimate the illuminant (Hurlbert, 1986), or the use of relative frequencies of colours
appearing together as a predictor (Long & Purves, 2003). However, no single theory seems
able to account fully for colour constancy (Foster, 2011; Kraft & Brainard, 1999).
Understanding the mechanisms which support colour constancy is addressed as a
perceptual question on the whole. In reality, colour for humans does not exist in the physical
uniform wavelength spectrum, but as fairly well-defined categories; each given a colour
name. The origin of colour names has been the source of much research, with evidence that
colour categories are universal to all humans (Berlin & Kay, 1969). There is also evidence of
categorical perception of colour in infants as young as 4 months old, broadly reflecting
categories of adults (Franklin & Davies, 2004). This suggests languages are shaped in
response to our perceptual representations. The Universal approach sees colour categories as
being arranged around focal colours (Berlin & Kay, 1969). Philipona and O’Regan (1996)
have suggested that prototypical examples of categories are so because they are the most
stable, and that this fact has led to their similar categorisation across languages. Conversely,
evidence that language shapes the way we see colour from cross cultural studies led to a far
more conceptual explanation (Roberson, Davies & Davidoff, 2000). This view sees shared
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
representations as resulting in colour categories, with colours built from boundaries
negotiated through language. Considerable research has made the arguments less
dichotomous, with an answer that lies somewhere between the two.
Categorical colour constancy was assessed using a sorting paradigm with adults
across various differently illuminated conditions (Olkkonen, Hansen & Gegenfurtner, 2009;
Olkkonen, Witzel, Hansen & Gegenfurtner, 2010). They concluded by linking colour
constancy with the ability to consistently name colours. They based their conclusions on
findings that only minor boundary changes occurred with illumination changes, and that
colour categories changed little between observers, or illuminations. This correlation
between naming consistency between individuals and illuminations in particular suggests
colour constancy and categories for colour naming are linked.
When exploring the interaction of language and colour, research has turned to
developmental studies to address this type of question (e.g. Franklin, Clifford, Williamson &
Davies, 2005; Franklin, Wright & Davies, 2009). Few studies to date (Dannemiller, 1989;
Dannemiller & Hanko, 1987) have examined the development of colour constancy in infants.
These suggest colour constancy is present in early life, with evidence of colour constancy in
infants at around 4-5 months of age. The development of categorical colour constancy poses
a number of important questions which, if answered, could add considerable understanding to
current theory. If categorical colour constancy patterns are unchanged through the lifespan,
this suggests perceptual origins, supporting universal theories. If however, these patterns
change through the acquisition of language, this would suggest categories are conceptual, and
formed by shared representations in language. This raises the question of what impact
learning the names of colours has on colour constancy.
Early studies suggested children cannot name colours consistently and reliably until
about 4-7 years old (Bornstein, 1985). In fact, more recent work shows children can
consistently comprehend and name the first nine main colours at around the age of three
(yellow, blue, green, purple, red, orange, black, pink and white), with brown and grey
following over the course of the next nine months (Pitchford & Mullen, 2002 & 2005). The
acquisition of colour terms is thought to be more difficult than acquiring other words such as
object words (Pitchford, 2006) due to its abstract nature (Kowalski and Zimiles, 2006) or an
attentional bias (Soja, 1994) toward shape. Interestingly though, this late mastery of colour
names stands in stark contrast to the early evidence of colour constancy in infants. This
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
timing difference between early perceptual colour representations, with those emerging later
from language, provides an opportunity to explore how they interact.
Bonnardel and Pitchford (2006) compared children aged 26-57 months with adults in
a colour sorting study. Stimuli were 100 Munsell1 chip samples which participants were
asked to sort into eight colour categories (red, pink, orange, brown, yellow, green, blue, and
purple). Children placed the chips into boxes decorated with a picture of a teddy bear and a
Munsell chip as an example of each colour category. Children were grouped according to
colour naming ability.
This study enabled comparison of the colour categories and boundaries from adults
and children with ‘beginning’, ‘developing’ or ‘accurate’ colour naming abilities. Bonnardel
and Pitchford concluded that there was little evidence for language influencing categorization
of colours, except with brown, which appeared to require some conceptual understanding
before consistent boundaries were found.
The current study aims to determine if adult categories are the result of concepts
learned as children, or have their basis in perception. The relationship between categorical
colour constancy and acquisition of colour terms will be examined. Perceptual origins will
be supported by little change during language acquisition; conceptual origins will be
supported by the emergence of adult like patterns. Children with partial colour naming
abilities will be asked to sort colours under different illuminations. Five key questions will
be used to guide the research.
How Consistently Can Children Categorise Colour?
Children’s categories would be expected to be less consistent than adults and with
more variability between illuminant changes, as categories are forming. As children are still
learning some of the key terms some colours may be incorrectly named and categorised.
1
Munsell Color system is a colour order system which divides colour into three dimensions; hue, value
(lightness), and chroma (colour purity). Hues are divided into 5 categories; red, yellow, green, blue and purple,
then with combination colours between each (for example the category between blue and purple is PB) with
ten increments between each of these resulting in a possible 100 hues. Munsell produce colour swatch books
with individual removable colour swatches/chips across the full range. These individual Munsell chips have
maximum dimensions of 2cm x 4 cm. Further information can also be found here http://munsell.com/
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Does Children’s Consistency Change During Language Acquisition?
Theoretically, if categorical colour constancy is conceptually driven and shaped by
linguistic colour categories, then this similarity to adult categories would be expected to
emerge over time as acquisition of colour terms becomes more stable. If categorical colour
constancy has a perceptual basis then it would be logical to expect learning colour words to
have little impact on these categories. The distribution of consistencies and the mapping of
the categories should be similar, even though categorization is likely to be ‘noisier’ than with
adults, resulting in lower consistency.
How Consistent Are Children When Illuminations Change?
The available research suggests children do have colour constancy, but no literature to
date suggests how well developed this is. It may not be as robust as that in adults which will
be demonstrated by the level of consistency between illumination conditions. High
consistency despite changing illuminations will suggest good colour constancy. If
consistency between illuminations and between individuals is high this would suggest that
colour constancy mechanisms are related to category formation.
Are Some Categories More Stable Than Others?
Individual colour categories may be more or less consistent than others; perhaps some
will be more stable under changing light conditions for children. Certainly there is evidence
this is the case in adults (Olkkonen et al., 2009; Olkkonen et al., 2010) after controlling for
category size. Larger categories would be expected to be more consistent as they have a
smaller proportion of hues as borders than as central (or focal) hues.
Are Boundaries Less Consistent Than Prototypes?
The Universalist view would predict that categories are built around some key focal
points (Berlin & Kay, 1969; Collier et al., 1976) most likely due to higher saturation. The
opposing view would suggest that boundaries are the critical decider, linguistically
determined, with prototype locations being influenced by where boundaries are set. Either
way, if prototypical chips represent the best example of each category, then it seems likely
that they will be located fairly centrally within categories. Categorisation consistency may
differ between children and between illuminants.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Method
Participants
Fourteen children (seven boys) aged 36-51 (M = 41) months, with English as their
first language and with no known visual deficiencies were tested. Seven completed all four
conditions, two completed three and five completed two or less.
Materials
For the initial colour naming and comprehension task rabbit flashcards were produced
(Pitchford & Mullen, 2002) on grey backgrounds and laminated. For colour naming,
individual rabbits wearing coloured clothes (focal colours from each of the eight selected
colours; red, green, blue, purple, yellow, orange, pink and brown) were used (Appendix A)
and for colour comprehension a central rabbit was pictured with eight coloured jumpers in a
circle around it (Appendix B) were used.
One hundred and sixty three glossy chromatic Munsell sample chips were used as
stimuli. These were always the highest chroma available, across 40 hues covering all hue
groups every 2.5 steps with lightness values of 3, 5, 6 and 8. These are shown in Figure 1.
Card shapes (jumper, shorts, or hats) with dimensions of approximately 4cm² were painted
grey (N5 Munsell colour) and the glossy Munsell (1966) colour chips attached. The reverses
of stimuli were coded for identification. A wooden board was painted in the same grey paint
and used to display all stimuli, including eight toy animals.
Figure 1. shows the Munsell chip collection. A further 3 were added to provide some prototypical reds at
value 4.
For the filtered light conditions, red and green Lee filters (http://www.leefilters.com)
were used to cover windows, either using a frame, or stapled directly over the window frame
and natural light was used for the daylight conditions.
Ishihara and Tritan plates were used to test for colour deficiency.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Illumination levels were measured using a specular reflectance standard using a
Minolta colour meter. These were averaged to provide CIE xyY values shown in table 1.
Table 1. Lee filter specifications with the corresponding average CIE xyY values. Means and standard
deviations are taken from across all testing sessions for each illumination
Y (cd/m²) mean
Illuminant
Filter
x mean (SD)
y mean (SD)
(SD)
Daylight
-
0.307 (0.021)
0.327 (0.02)
125 (89)
Red
35 Light pink
0.345 (0.009)
0.301 (0.005)
78 (39)
Green
138 Pale green
0.257 (0.123)
0.353 (0.016)
65 (28)
All data were recorded using templates (Appendices C,D,E & F)
Design
A pilot was conducted with two children, which highlighted the need for three
additional colour chips for ‘red’. Subsequently 163 were used.
Naming and comprehension. The comprehension task was completed by showing
children the rabbit flashcards surrounded by different colour clothes, asking them to ‘point to
the colour red’ (yellow, green, etc.) and recording their responses. The naming task was
completed by showing children flashcard single rabbits and asking them to name the colour
of each of the eight rabbits. Their responses were again recorded.
Main task. A repeated measures design was used across a maximum of 4 different
illuminant conditions; daylight, red, green and a second daylight. The dependent variable
was the consistency with which each chip
is re-categorised across varying
illuminations and participants.
Illumination conditions were separated in
most cases by one week and no child
completed more than one condition in a
day. The first condition was always
daylight, but subsequent conditions were
counterbalanced across participants.
Figure 2. Example of experimental set up
Each room was cleared to remove as many distractions as possible. The board was
positioned to take advantage of the best natural light; ensuring stimuli would be well lit for
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
the child. Animals were placed in plastic boxes along the back of the board (Figure 2.). The
arrangement of the animals and ‘favourite colour’ allocated for each condition and
participants were counterbalanced. Colour name labels were positioned at the rear for the use
of experimenters during testing. Stimuli were laid out with the hue circle running from one
side to the other, darkest chips closest to the child. The hue circle was either centred with
pink or green, and this was alternated across conditions for each child.
Children were asked to sort the colour chips into categories and then identify a
prototype from each category. Once children had completed the task and left, stimuli from
each category were turned over and photographed as a category, so that recording and coding
of data could take place later.
Colour deficiency tests were administered before the first condition by asking children
to trace the coloured line on Ishihara plates and to point to the different corner on Tritan
plates. Participant information and data was collected using forms (Appendices 3-6).
Procedure
Materials were arranged as described above and light measurements taken and
recorded. Children for whom consent had been obtained were approached and asked if they
would like to come and play. Assenting children were first presented with the
comprehension task, followed by the naming task and colour deficiency tests.
Main colour task. Children were asked if they would like to play a game with the
animals. The experimenter explained that each animal would like to collect a particular
colour and children were asked to sort the stimuli into colour categories. On completion, the
experimenter asked the child to select the best example from each category for the animal.
Children were thanked and given a picture to colour in. Light levels were retested and
recorded once the child had left. All testing sessions were conducted between the hours of
9.30 and 3.30 to ensure that lighting conditions were as consistent and light as possible.
The procedure for the main task was repeated for the four illuminations where
children agreed. On the final session, the naming and comprehension test was repeated.
Ethical considerations. Each nursery was visited to provide details of the study
(Appendix G), and show the stimuli, flashcards and toys. Parents were provided with an
information (Appendix H) and consent letter (Appendix I) regarding the experiment and
10
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
requesting consent for their children’s participation. Children whose parents’ had consented
to their participation were approached in the nursery setting and asked if they would like to
participate in some games. Children’s assent was sought separately for each of the
conditions. Children were thanked after each session and informed that they would be asked
again next week. All participant data was anonymised. Ethical approval was obtained from
the University of Sussex Ethics board and British Psychological Society guidelines were
complied with at all times. A satisfactory CRB check was obtained for experimenters.
Results
Of the eight colours tested there was no significant difference between children’s
initial (M = 8, SD = 0) and final comprehension scores (M = 8, SD = 0) or initial (M = 7.9, SD
= .32) and final naming scores (M = 7.8, SD = .42), t(9) = .56, p = .59, ns. Many children
performed at ceiling for this task.
Main Task
Guide to analysis. Frequencies with which each colour chip was re-categorised as
the same colour across illuminations or by other children were calculated to provide
‘consistency’ scores. A score of 1 reflects perfect consistency, 0.5 reflects 50% consistency
and 0 reflects no consistency. High consistency between illumination changes is evidence of
colour constancy. This was calculated for the two daylight conditions first to determine the
degree of variability due to retesting, then for all other pairs of illuminant conditions and
between individuals. Consistency of categorisation between participants is referred to as
consensus. Where adult data is referred to, this was obtained from Olkonnen and colleagues
(2010) and is based on a matched sample of Munsell chips, unless stated otherwise. Where
‘maturity index’ is referred to this was calculated in the same way, but with adult daylight
data compared to child daylight data to provide a consistency score.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
A
B
Figure 3. Average colour categories over all illuminations and all participants. Black lines show
boundaries of categories. Hue varies from left to right and value (lightness) increases from bottom to top.
Circles represent the prototypical loci, larger disks were selected more frequently than smaller disks. In
adult data (A) consistency of less than 90% is reported as % consistency and values above 90% are
omitted. Child data (B) is from the current study. Consistency of below 60% is represented by a lighter
shade and above 60% in the darker shade. At lightness level 4, only three chips were used.
How consistently can children categorise colour? Individually, children varied
somewhat in their consistency between illuminants, certainly more than adults (see Figure 3);
with mean consistencies across all illuminants ranging from 0.53 to 0.81 (M = 0.69, SD =
0.11). Similar adult data found a higher mean consistency of 0.89 (although this included
four filtered conditions rather than two, and a larger chip selection). Figure 4 shows the
variation across conditions for each participant and also that between illuminations variations
were not confined to any particular illumination colour. Interestingly some of the children
with lower consistencies were also those who completed fewer conditions.
12
Mean consistency (+/-1 SEM)
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Daylight1
-2
Daylight1
-Red
Daylight1
-Green
Daylight2
-Red
Daylight2
-Green
P1
P2
P3
P4
P5
P6
P7
Participant
P8
P9
P10
P11
P12
Maturity
index
Figure 4. Mean consistency scores for each participant for each illumination pair and maturity index. The
maturity index is a measure of the consistency between adult and children daylight categorisation for each
chip. (Missing participants completed insufficient conditions for comparison.)
Does children’s consistency change during language acquisition? The consistency
between children and adults in the daylight conditions were calculated to provide a maturity
index. This reflects how similar the children’s categories are to that of the adults. Average
age in days at testing was also calculated for each child and is shown in Table 2. There was
no significant relationship between age and the maturity index, r = -.24, p = .16, ns or age and
categorisation consistency in the daylight condition which was used as a baseline condition, r
= -.14, p = .4, ns, but this consistency was positively and significantly related to the maturity
index, r = .68, p < .01, meaning that classification becomes more consistent as children’s
categories begin to resemble those of adults.
Table 2. Mean age in days at testing across total number of conditions completed where available.
Participant number
Mean age at testing in
Gender
Number of
days (SD)
Conditions
1
1297 (8.66)
M
4
2
1113 (7)
M
3
3
1198 (8.66)
F
4
5
1211 (18.41)
M
4
6
1268
F
1
7
1110 (16.15)
F
4
8
1125 (17.62)
M
3
9
1392 (7.21)
M
3
10
1226 (9.04)
F
4
11
1468 (9.04)
F
4
12
1180 (5.91)
F
4
13
1553
F
1
14
1256 (4.95)
M
2
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
How consistent are children when illuminations change? Children’s categorisation
for daylight, red and green illumination conditions are shown in Figure 5. Consistency across
illuminants was derived by calculating individual consistencies for each illumination then
averaging each illuminant change across children. This was significantly related to
consistency across illuminants for adults, r = .63, p < .01 suggesting similar patterns of
constancy occurred between illuminations for both adult and child samples.
A
B
C
Figure 5. Average colour categories for all children for aggregated neutrals (A), red (B) and green (C)
filtered conditions. Black lines show category boundaries. Hue varies from left to right and value
(lightness) increases from bottom to top. Circles represent the prototypes; larger disks were selected more
frequently than smaller disks. Consistency < 60% is represented by a lighter shade and > 60% the darker
shade.
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
The effect of the illumination changes was calculated for each of the illuminations by
comparing the consistency between one pair of conditions with that of another pair. If a child
is colour constant, similar consistency would be expected between both daylight conditions
and filtered conditions. A lack of colour constancy would be represented by higher
consistency between the two daylight conditions and lower consistency between daylight and
a filtered condition as it would be expected that some colours would appear to be different
under the altered illumination. Ratios were calculated between the various illuminations for
each participant by dividing the consistency from coloured conditions with those of the
repeated measures of daylight (see Table 3). Some ratios were 1 or greater, so some children
performed better between illumination changes than between the daylight repeated measures.
There were no significant relationships between these and age at testing or category maturity,
so this analysis shows categorical colour constancy does not appear to improve with age or
maturity of categories.
Table 3. Ratios between illumination change pairs. In each column the average consistency between the top two
conditions is divided by the average consistency of the bottom two conditions. Ratios over 1 are highlighted.
all
daylight &
daylight &
daylight2 &
daylight2 &
illuminations/
red/
green/
red/
green/
repeated
repeated
repeated
repeated
repeated
Participant
daylight
daylight
daylight
daylight
daylight
measures
measures
measures
measures
measures
0.94
0.96
0.95
0.95
0.92
1
3
1.09
1.20
1.05
1.18
0.94
5
0.95
0.97
0.95
0.86
1.01
7
0.92
0.92
1.01
0.87
0.88
8
0.74
0.67
-
0.81
-
9
1.17
1.17
-
1.18
-
10
0.98
1.00
0.99
0.99
0.95
11
0.96
1.01
0.92
1.03
0.89
12
0.98
1.04
1.01
0.94
0.95
Are some categories more stable than others? The consistency of each colour
category is shown both across illumination and across participant and illustrated by Figure 6.
Both follow a similar pattern with an almost perfect correlation, r = .98, p < .01. There was a
significant difference between the consistency of the various colour categories, F(7, 67.16) =
3.37, p = .004, (the assumption of homogeneity of variance was violated so the Welch F ratio
is reported). Although the greatest consistency occurred for green, blue also appears to be
highly consistent, as with purple, but post hoc tests revealed no significant differences for
individual comparisons. Consistency appears lower at some category boundaries, but the
15
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
lowest consistency appears to coincide with the points at which different lightness levels
account for the variation in hue, such as with yellow and brown.
1
0.9
0.7
0.6
0.1
Pink
Purple
Green
Across
Illum
Yellow
0.2
Brown
0.3
Orange
0.4
Blue
0.5
Red
Consistency index
0.8
Across
Partic
0
Munsell hue
Figure 6. Across illumination and across participant classification consistencies for each of the Munsell
hues (+/- 1 SEM). Value has been condensed across hues and chroma is the highest available at all
times. Category centres for all illuminations have been added for clarity, and are based on aggregated
classifications for all children across all illuminations.
Are boundaries less consistent than prototypes? To compare boundaries, the most
frequently chosen category for each chip in the two neutral conditions for all children was
used (figure 1.). Prototypes were those selected by the children as most representative of
each colour category. Unlike in adult data, some prototypes were also boundary colours (e.g.
Figure 3 B and Figure 5 A, B & C), these were excluded from analysis, leaving 36 boundary
chips and 41 prototype chips. A two way 2 (consistency type: illumination or participant) x 2
(category status: boundary or prototype) mixed ANOVA was completed to address this
question. There was a significant main effect of consistency type, F(1, 75) = 38.12, p < .001,
so consistency was different between participants and between illuminants. There was also a
significant main effect of category status, F(1, 75) = 55.25, p < .001, but a non-significant
interaction between consistency type and category status F(1, 75) = .33, p = .57, ns. Figure 7
shows these results.
16
Mean consistency score (+/- 1 SEM)
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Boundary
Prototype
Participant
Illuminant
Consistency type and category status of chip
Figure 7. Mean consistency scores for participants and illuminants for chips categorised as
prototypical colour chips or boundary colour chips.
Discussion
Results showed children display a high level of categorical colour constancy and that
despite increased variability due to incomplete colour knowledge, their categories closely
resemble those of adults. Consistency between children and for individual children over
varying illuminations, were both very similar and reflected previous findings in adults
(Olkkonen et al., 2010). Individual colour categories reflected those of adults too, both
between participants and between illuminations, but prototypes were widely dispersed and
lacking consensus between participants, unlike in adults.
Naming and Comprehension
There was no evidence of a significant change in naming or comprehension of colours
over the experimental period but many children achieved ceiling performance which limited
the findings. Sadly, the ceiling level performance demonstrated by the majority of the
children may have obscured any interesting results. Ideally, this could have been used to
divide participants into two groups for comparison, but the task was too easy. This may also
have been evidence of an improvement in colour naming and comprehension over the
experimental time frame.
How Consistently Can Children Categorise Colour?
On the whole children appeared reasonably consistent with their categories, but over
repeated testing sessions children varied in the consistency with which they categorised the
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
chips. It seemed that those who were the least confident with their colours were also those
least likely to complete the conditions. Children appeared to categorise colours in a way that
is remarkably similar to adults, although the additional variability children displayed resulted
in considerably lower consistency than with adults.
Pitchford and Mullen (2002) found that children reliably learn 9 basic colours
(yellow, blue, green, purple, red, orange, black, pink and white) during age 35.6 to 39.5
months, with brown and grey following about 9 months later. The children tested in the
current study were consistent with these claims on the whole. During testing it appeared that
colour labels which children were less certain with, such as brown, grey or black were
frequently used to categorise colours they were unsure of. This is consistent with the idea
that children eliminate possible meanings for words by assuming they are mutually exclusive,
(e.g. Markman & Wachtel, 1988). In this example if a child is unsure exactly what
constitutes ‘brown’, then is presented with an unusual colour, but is already confident about
red and blue, then they will assume this unusual colour must belong to the unknown category;
brown.
In the current study children in fact suggested other categories of colour, such as
peach, silver and gold, sometimes with great precision, and sometimes without. Interestingly,
peach was named and categorised by several children in one nursery and no other, and silver
and gold in two nurseries and no other, all suggesting some ‘locally’ learned input. At the
setting in which peach featured highly, nursery staff identified peach as the colour paint
recently used for self-portraits as skin colour, explaining the origins of this one extra category
to these particular children.
Does Children’s Consistency Change During Language Acquisition?
Chronological age and maturity were not significantly correlated, so adult like
categories did not develop directly with age. As age was calculated as a mean of each child’s
age at each testing session, the total experimental time frame varied for individuals. It could
be that shorter experimental timeframes improved (or hampered) consistency with practice.
It is also possible that the experience of sorting the colours may have improved the children’s
attention to colour.
Age was also not related to children’s categorisation consistency so children did not
improve their consistency in line with their age. The maturity index was however related to
18
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
children’s consistency, so the correlational data suggested that child consistency reflected
adult patterns rather than being a product of age. Categorical colour consistency then seems
to be linked to the conceptual acquisition of categories arising from language. Perhaps
children’s categories during colour term acquisition are not changing in line with age, but
rather beginning to reflect adults’ linguistic categories.
How Consistent Are Children When Illuminations Change?
Consistency between illuminant changes essentially indicate colour constancy, so this
question addresses to some degree how ‘colour constant’ children are. When illuminations
changed, children’s consistency was correlated with adult categories once again; suggesting
categorical colour constancy followed a similar pattern in children to adults. In the absence
of colour constancy, with green illuminations, colour maps of the perceptual appearance of
the chips would likely reflect a larger green area, perhaps less yellow. For the red
illumination, a larger red, more pink, and purple might be expected, but in reality the colour
maps show little obvious change, so both visually and statistically children displayed fairly
robust colour constancy.
When comparing the ‘consistencies of illumination changes’ and ‘consistencies with
no illumination changes’, there was a great deal of variability. The most illustrative of these
comparisons should have been comparing daylight-red or daylight-green (illuminant change)
with the two daylight (no illuminant change) conditions, and most participants performed
very close to ‘1’ which means no difference and therefore good colour constancy. However
the presence of several ratios of above ‘1’ shows that sometimes children actually performed
better between illumination changes. Simply put, between illumination changes some
children appeared to perform better than between the daylight repeated measures, which is
unexpected. There was no significant relationship between these results and age or maturity,
it seems most likely that these can be accounted for by the experimental timeframe providing
practice effects and helping to consolidate children’s concepts of the categories ‘on-line’.
Are Some Categories More Stable Than Others?
Consistency across illuminations and consensus among participants were both
remarkably similar, a pattern that was also found by Olkkonen and colleagues (2010). Given
the higher variability in children’s data, this seems even more surprising. The degree of
consistency across the eight categories varied significantly. It could be that larger categories
19
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
(like green) are more stable than small ones (like red) as a smaller proportion overall is close
to a boundary. Consistencies might be expected to dip at boundaries, and be highest in
category centres and whilst this is so in some cases it does not seem as though the troughs in
Figure 7 are all consistent with boundaries. Aggregating lightness levels may have hidden
this, in fact some of the lowest consistency was found around the brown, red and yellow hues
where categories are divided by lightness rather than simply hue. Olkkonen and colleagues
(2010) found that consistency decreased with lightness and increased as chroma increased.
The current study did not consider the impact of chroma, but by using only the highest
chroma, consistency levels should be maximised. High saturation levels have been
implicated as significant if categories are universal (Collier, 1976; Regier & Kay, 2007),
providing the external ‘peaks’ in colour space and associated with the basic focal colours.
Are Boundaries Less Consistent Than Prototypes?
If prototypes represent the typical example of a colour, then they would be expected to appear
fairly centrally within a category. In reality this was not the case, prototypes were widely
distributed. It may be that aggregation of data has caused a lack of consensus between the
participants to appear this way. The consistency of boundary chips was significantly lower
than prototypes for children, but many boundary colours were also nominated as prototypes
and were less localised than in adults. The ‘perceptual’ prediction that categories are built
around focal colours is supported with this data, but the lack of consensus between
participants may undermine this finding.
Basic colour terms were used here, which in practice was not always the case with the
children, with names like peach, gold and silver evidenced. If, for example additional
categories (turquoise, peach, lilac…) which have been found in free-choice naming
experiments were available (Boynton & Olson, 1987, Roca-Vila, 2012), then boundaries
would have been differently located. This is after all, a time when children are learning
colour terms and so as additional terms become available, some boundaries may be changing.
General Discussion
In terms of the key questions this study aimed to address, it seems that categorical
colour constancy in children is rather like that of adults in many ways. Previous research had
provided evidence that colour constancy was present from very early on in infants, possibly
developing alongside colour vision generally. The design was ambitious, with children
20
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
sorting 163 chips on four occasions, providing far finer calibration of colour than has
previously been attempted elsewhere in colour sorting tasks (Bonnardel & Pitchford, 2006).
Colour constancy is thought to rely on perceptual mechanisms (Amano & Foster,
2011; Hurlbert, 1999), which provide us with consistency of colours across illumination
changes that are near perfect. Categorical perception on the other hand is shown to be subject
to at least some degree of moulding from the cultures we are immersed in. So if when
categorical colour constancy is considered, the effect of learning the colour names and what
they refer to results in changes, then this could provide evidence that categorical colour
constancy is conceptually driven.
Recent claims have been made that perceptually stable areas of colour space
correspond with the focal areas of red, yellow, green and blue (Philipona & O’Regan, 2006).
The findings here support other work (Olkkonen et al., 2009; Olkkonen et al., 2010) which
has found that consistency between individuals and across repeated measurements with the
same individual are strongly related. This provides additional evidence to support the idea
that this perceptual stability provides some ‘anchoring’ for colour categories. The evidence
here also points to a change taking place over the course of colour term acquisition which
sees adult-like categories emerge, rather as a result of learning than as a product of age.
Ideally, if it had been possible to divide the children based on their colour naming and
comprehension skills, some comparison may have provided evidence of ‘before’ and ‘after’
group differences, in addition to correlational analysis. Ceiling performance ruled this out,
leaving correlational analysis as the main tool in answering this question. If children’s
consistency improves as categories take on adult form and neither of these things are
significantly related to age, then children’s newly acquired concepts of colour categories are
reflected in the improvements in categorisation consistency. This suggests a trajectory
toward conceptual categories. This could be taken to show adult categories emerge from
those learned during language acquisition. This adds significantly to the still widely debated
influence of language on how we see colour.
Whilst in the current study gender was not analysed, this could certainly be explored
in further analyses. Substantial gender differences (Bimler, Kirkland & Jameson, 2004;
Roca-Vila, 2012) in use of colour terms have been found and although varying reasons have
been offered , both physiological and cultural, this could be another indicator of cultural
influence (Moore, Romney & Hsai, 2002). If gender differences emerge during colour term
21
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
acquisition this would provide additional support for the influence of language and culture on
how we see colour.
This study is the first of its kind, considering categorical colour constancy origins
from a developmental perspective. It provides, not only a very valuable and detailed picture
of the state of toddlers categorical colour constancy which is currently not accounted for
elsewhere in developmental or vision literature, but most significantly provides insight into
the origins of adult categorical colour constancy. This study heralds exciting new evidence
suggesting a story of early category formation reliant on perceptual factors, such as the
enhanced stability of some focal colours, but moulded during language acquisition by what
they learn from others. So despite a perceptual beginning, it seems adult colour categories
and categorical colour constancy are shaped by what we learn at the tender young age of
three and a bit.
22
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
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Franklin, A., Clifford, A., Williamson, E., & Davies, I. (2005). Color term knowledge does
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Franklin, A. & Davies, I. (2004). New evidence for infant colour categories. British Journal
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Franklin, A., Wright, I., & Davies, I. (2009). What can we learn from toddlers about
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Moore, C. C., Romney, A. K., & Hsai, T. (2002). Cultural, gender, and individual
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EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix A
Colour comprehension test. Available in Pitchford & Mullen 2002.
26
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix B
Example flashcard for colour naming. From Pitchford & Mullen 2002.
27
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix C
Overview template for each participant
ID
Nursery
Start date
Ishihara
Comprehension
Ini
ID
Naming
N1
Pre
Post
Centred
pink
Set-up Photo
Order:
green
Main (sat)
Unsat
Session:
Session:
Main (sat)
Unsat
Session:
Session:
Main (sat)
Unsat
Session:
Session:
Main (sat)
Unsat
Session:
Session:
R
Pre
Post
Centred
pink
Set-up Photo
Order:
green
G
Pre
Post
Centred
pink
Set-up Photo
Order:
green
N2
Pre
Post
Centred
pink
Set-up Photo
Order:
green
Fin
ID
Comprehension
(post)
Naming (post)
(Ishihara)
28
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix D
ID
Nursery:
Nursery ID:
ID:
Birthday (age):
Gender:
Nationality:
Mother Tongue:
(mono- / bilingual)
Start date:
Start time:
(first session)
(first session)
Experimenter:
Assistant:
(Defic. & Lang.)
(Defic. & Lang.)
Ishihara
a.) Daltonism
Let child choose one of two plates of each type; mark chosen one.
Type
Practice
Plate Nr.
38
Green-Orange
Orange-Green
37
35
36
34
Black-Red
26
27
Correct
If indications of daltonism: Test the other one in each pair; if successful, test one of the difficult ones 32 or 33:
Type
Green-Orange
Orange-Green
Plate Nr.
37
35
36
34
Black-Red
26
27
Difficult
33
32
Correct
b.) Tritan
Plate
Nr. 0
Nr. 3
Nr. 2
Nr. 4
Nr. 5
(practice)
(medium)
(easy)
(difficult)
(very diff)
Correct
If no success with Nr. 3: show correct answer with plate Nr. 1; then proceed with the easy Nr.2, and test with
Nr. 4.
29
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Language (pre)
Random order of colours; 2 for each plate.
a.) Comprehension
Cat.
Pink
red
orange
yellow
Green
brown
grey
black
white
red
orange
yellow
Green
brown
grey
black
white
blue
Answer
Cat.
Purple
Answer
b.) Naming
Cat.
Pink
blue
Answer
Cat.
Purple
Answer
30
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix E
Template to record each sessions data
ID:
Date:
Condition:
Start-Time:
End-Time
Experimenter:
Assistant
Measurement of illumination
White-Standard:
Munsell N9,5 ----- Reflectance standard
Measurements:
Pre/Post
Y
X
y
Comments
Categorisation
Spatial Arrangement:
Green-centred ----- Pink-centred
Teddy-Colour-Order:
Template
Row
Hue-Full
Animals
Colours
Prototypes
Neutral
Animals
Colours
GREY
BLACK
WHITE
Prototypes
31
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix F
Template to record final session including language test.
ID:
Name:
End date:
(All sessions)
Start time:
(Last session)
Experimenter
Assistant
(Lang.)
(Lang.)
Language (post)
a.) Comprehension
Cat.
Pink
red
orange
yellow
Green
Purple
brown
grey
black
white
Pink
red
orange
yellow
Green
Purple
brown
grey
black
white
blue
Answer
Cat.
b.) Naming
Cat.
blue
Answer
Cat.
Turn
32
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Ishihara (if indications for deficiency)
a.) Daltonism
Let child choose one of two plates of each type; mark chosen one.
Type
Practice
Green-Orange
Orange-Green
Black-Red
Plate Nr.
38
37
35
26
36
34
27
Correct
If indications of daltonism: Test the other one in each pair; if successful, test one of the difficult ones
32 or 33:
Type
Green-Orange
Orange-Green
Black-Red
Plate Nr.
37
35
26
36
34
Difficult
27
33
32
Correct
b.) Tritan
Plate
Nr. 0
(practice)
Nr. 3
(medium)
Nr. 2
(easy)
Nr. 4
(difficult)
Nr. 5
(very diff)
Correct
If no success with Nr. 3: show correct answer with plate Nr. 1; then proceed with the easy Nr.2, and
test with Nr. 4.
33
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix G
Example nursery recruitment letter which was printed on headed paper.
Sussex Colour Group
School of Psychology
University of Sussex
Sussex House
Brighton
BN1 9RH
Date
Dear *****,
I am a researcher of the Sussex Colour Group at the University of Sussex and am doing
research on how toddlers see colours. The research project is investigating whether learning
the names of colours influences how colours are seen.
I am looking for children aged between 36 and 42 months to take part in this research. I will
ask the children to complete two child-oriented, fun tasks, which measure children’s ability to
name and sort colours using animal characters.
These tasks would be completed with children on a one-to-one basis at the nursery over a few
days. The sessions can be at mutually convenient times and each individual session would
take no longer than half an hour. I would of course provide the nursery with a summary of
the research findings. The research project has been approved by the University of Sussex's
ethics committee.
I will ring you in the next couple of days to discuss whether it would be possible to conduct
this research in your nursery.
Yours sincerely,
34
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix H
Information letter provided to parents and printed on headed paper.
INFORMATION SHEET
Does learning colour names influence how children see colour?
I am a researcher for The Sussex Colour Group at the University of Sussex. We are
conducting a research project looking at whether learning the words for colours, influences
how children see colours. To investigate this, I will ask children to complete a quick and fun
colour game on up to four occasions.
One game will involve naming the colours of clothes on an animal character and will take
less than five minutes. The main game (which will be repeated on different days) will
involve asking children to sort colours into different groups.
Overall, the sessions will take a total of around half an hour each, and will be conducted at
your child’s nursery, during their usual nursery time.
Risks/benefits and use of the study
There are no known risks of taking part - the fun tasks are similar to the kinds of pre-school
games that are played in nursery. If you and your child wish to take part in the research, then
I will send you a summary of the study once it is complete. In the long term, the research
aims to help us understand how children see the world around them.
Right to withdraw
If at any time, and for any reason, you or your child wish for the session to stop this is fine,
and you are free to withdraw your child's data from the study up until the study is submitted
for publication. All information and data from the session will be stored, managed and
destroyed in accordance with the Data Protection Act (1998). All data from the session will
be confidential — your child will be given a participation number, but this will be kept
separate from this consent form so we will not be able to link your child's name to the
number.
Please note: if you have a concern about any aspect of your participation, please raise this
with the investigator: ****, email: *****@sussex.ac.uk, or with the research supervisor: Dr
Anna Franklin, tel: 01273 678885, email: anna.franklin@sussex.ac.uk
This research has been approved by the School of Psychology Ethical Review Board.
35
EFFECTS OF LANGUAGE ON COLOUR CONSTANCY
Appendix I
Consent form
I the undersigned voluntarily agree on behalf of my child to take part in the study of whether
learning colour names influences how children see colour.
I have read and understood the Information Sheet provided. I have been given a full
explanation by the investigators of the nature, purpose, location and likely duration of the
study and of what my child will be expected to do. I have been given the opportunity to ask
questions on all aspects of the study and have understood the advice and information given as
a result.
I understand that all personal data relating to volunteers is held and processed in the strictest
confidence, and in accordance with the Data Protection Act (1998).
I understand that I am free to withdraw my child from the study during the session, or
withdraw my child's data before the study is submitted for publication without needing to
justify my decision and without prejudice.
I confirm that I have read and understood the above and freely consent to my child
participating in this study. I have been given adequate time to consider my child's
participation and agree to the study.
Please email me if you would like to receive a summary of the study once completed. Note
that we will not disclose individual data, but only group-level analysis.
Your name
…………………………………………………………………………………………..……....
(BLOCK CAPITALS)
Child's name
……………………………………………………………………………………………..……
(BLOCK CAPITALS)
Nursery representative…………………………………………….....................................
Signed………………………………………………………………………………………
Date ………………………………………………
Name of researcher / person taking consent
…………………………………………………(BLOCK CAPITALS)
Signed
………………………………………………………………………………………………
Date ……………………………………………….
36