Difference test sensitivity - Comparison of three versions of the duo-trio method requiring different memory schemes and taste sequences.pdf - Artykuły - janocz

Food Quality and Preference 19 (2008) 97–102

www.elsevier.com/locate/foodqual

Diﬀerence test sensitivity: Comparison of three versions of the

duo–trio method requiring diﬀerent memory

schemes and taste sequences

Hye-Seong Lee, Kwang-Ok Kim *

Department of Food Science and Technology, Ewha Womans University, Seoul 120-750, South Korea

Received 30 January 2007; received in revised form 21 May 2007; accepted 9 July 2007

Available online 6 August 2007

Abstract

The duo–trio test is a simple non-directional diﬀerence test method suitable for discriminating subtle diﬀerences between confusable

stimuli. It is suitable for consumers as well as trained panelists. In the present study, the inﬂuence of memory and tasting sequence in the

duo–trio was investigated, using various low concentrations of NaCl in a roving discrimination design. Three versions of duo–trio pro-

tocols were considered. The ﬁrst protocol was the traditional duo–trio with the reference tasted ﬁrst (DTF). The second protocol was the

duo–trio with the reference tasted in the middle, between the two test samples (DTM). The third protocol was the duo–trio with the

reference tasted twice, ﬁrst and last as a reminder (DTFR). In some conditions, the higher concentration of NaCl solution was the ref-

erence (W-odd); in others, the lower concentration was the reference stimulus (S-odd). Calculated d 0 values indicated a superior perfor-

mance for the DTFR over the DTF and DTM. In the DTF, S-odd yielded a lower d 0 than W-odd, probably due to NaCl taste

adaptation. In the DTFR, the eﬀects of adaptation were counterbalanced for all the stimuli including the reference, resulting in no sig-

niﬁcant sequence eﬀect. In the DTM, the sequence of the ﬁrst two stimuli in the test had a signiﬁcant eﬀect on the performance, probably

due to the decision strategy used for the protocol. Manipulation of the reference in the duo–trio test introduces issues such as attention as

well as memory and adaptation.

Keywords: Diﬀerence tests; d 0 ; duo–trio; Memory; Sequence eﬀects; NaCl taste adaptation; Cognitive decision strategy

1. Introduction

characteristic of not having to describe what constitutes the

diﬀerence. However, they diﬀer in that same–diﬀerent test

involves two stimuli while the triangle involves three.

Considering diﬀerence tests, three main issues can be

identiﬁed; cognitive strategies, the sequence of tasting, and

memory eﬀects. Regarding cognitive strategies, a Thursto-

nian context can be invoked. It is generally assumed that

the duo–trio test as well as the triangle test uses what has

been called the ‘comparison of distances’ cognitive strategy

( Ennis, 1993; Lee & O’Mahony, 2004; O’Mahony, Mas-

uoka, & Ishii, 1994 ). It is necessary to know the cognitive

strategy for the computation of d 0 values. Because of this,

research into cognitive strategies is important.

The second topic concerns the sequence of tasting. This

has been described by the Sequential Sensitivity Analysis

The duo–trio test is a commonly used three stimulus dif-

ference test in which the attribute that diﬀers is not speciﬁed

( ASTM, 1968; Lawless & Heymann, 1996; Meilgaard,

Civille, & Carr, 1991; Peryam, 1958 ). The duo–trio is partic-

ularly useful for many important academic and business

objectives such as quality control, ingredient or process

changes, and storage or packaging changes which often

involve subtle multidimensional diﬀerences between stimuli.

The same–diﬀerent test and the triangle test share the same

* Corresponding author. Tel./fax: +82 0 2 3277 3095.

E-mail address: kokim@ewha.ac.kr (K.-O. Kim).

doi:10.1016/j.foodqual.2007.07.004

H.-S. Lee, K.-O. Kim / Food Quality and Preference 19 (2008) 97–102

(SSA) model ( Lee & O’Mahony, 2007a; O’Mahony &

Odbert, 1985 ) as well as conditional stimulus model ( Ennis

& O’Mahony, 1995 ). The SSA model predicts for a distilled

water/low concentration NaCl system that a duo–trio with

a weaker (water) reference (S-odd) would give superior per-

formance to one with a stronger (NaCl) reference (W-odd)

( O’Mahony & Odbert, 1985 ).

The third topic concerns memory. The memory problem

in diﬀerence tests has been discussed in reviews of Thursto-

nian modeling ( Lee & O’Mahony, 2004; O’Mahony &

Rousseau, 2002 ). A consideration of memory or forgetting

eﬀects would predict that a diﬀerence test with two stimuli

would give superior performance to one using three stimuli.

This can be argued from two points of view: memory decay

and interference. For the former, it can be argued that in a

diﬀerence test with two stimuli, the ﬁnal stimulus is com-

pared to the decaying memory trace of the adjacent ﬁrst

tasted stimulus. In a test with three stimuli, the ﬁnal stim-

ulus is compared with the decaying memory trace of the

adjacent second tasted stimulus and the even more decayed

memory trace of the ﬁrst tasted stimulus. Performance in

this triadic test would be expected to be inferior.

A second argument regarding inferior performance for

the triadic test would be that while tasting the ﬁnal third

stimulus, the memory traces of the initial two stimuli would

be distorted because of their mutual interference. Lau,

O’Mahony, and Rousseau (2004) working with triangle

tests, showed that this interference eﬀect was more impor-

tant than mere stimulus decay.

Comparisons have been made of the performance on

three stimulus and two stimulus tests. Dessirier and

O’Mahony (1999) and Rousseau and O’Mahony (1997)

reported that the three stimulus 3-AFC yielded lower d 0

values than the two stimulus 2-AFC. Although this could

be due to memory eﬀects, the comparison is complicated

because 2-AFC procedure has favorable sequences.

Although SSA predicts superior performance of the trian-

gle test over the same–diﬀerent test, based on sequence

eﬀects, it has been found that triangle test resulted in equal

or lower d 0 values than same–diﬀerent test, suggesting the

importance of memory eﬀects ( Kim, Jeon, Kim, & O’Mah-

ony, 2006; Kuesten, 2001; Lau et al., 2004; Rousseau &

O’Mahony, 2000, 2001; Rousseau, Meyer, & O’Mahony,

1998; Rousseau, Rogeaux, & O’Mahony, 1999; Rousseau,

Stroh, & O’Mahony, 2002; Stillman & Irwin, 1995 ). Yet,

memory eﬀects would not have appeared to dominate

sequence eﬀects when the duo–trio and same–diﬀerent test

had comparable d 0 values ( Kim et al., 2006; Rousseau

et al., 1998 ). Again, this comparison is complicated by

tau-variance with the same–diﬀerent test.

Interestingly, despite comparable expected memory and

sequence eﬀects, the duo–trio was shown to elicit higher d 0

values than the triangle test ( Liggett & Delwiche, 2005;

Rousseau et al., 1998 ). This could be chance results or it

could suggest some further factors.

The duo–trio with the reference presented ﬁrst, was orig-

inally developed by the Joseph E. Seagram Quality Labora-

tory in 1941 ( Peryam & Swartz, 1950 ). Compared with the

triangle test, the duo–trio could be viewed as a simpler test

because more information is provided: namely, the refer-

ence stimulus will not be the ‘odd’ one.

Rousseau et al. (2002) introduced a modiﬁcation of the

duo–trio test. For this protocol, the reference stimulus was

tasted in the middle of the triad. They named the test the

DTM (Duo–Trio Middle). They compared the perfor-

mance of the DTM with the traditional duo–trio test using

an orange ﬂavored beverage with diﬀerent concentrations

of sugar and found that the DTM elicited signiﬁcantly

higher d 0 values. They hypothesized that the memory load

for the DTM was reduced because the two test stimuli were

evaluated immediately adjacent to the reference.

Considering the traditional duo–trio, should distortion

of the memory for the ﬁrst (reference) stimulus be a prob-

lem for the assessment of the second test stimulus (third

tasted stimulus), the duo–trio could be modiﬁed by repeat-

ing the reference stimulus at the end of the test as a remin-

der. As with the DTM, each test stimulus would be tasted

adjacent to the same reference. Such a test will be called the

DTFR (Duo–Trio with reference given First and last as a

Reminder). The tasting sequences for the DTM and DTFR

are diﬀerent. The question becomes whether the perfor-

mance elicited by the DTM and DTFR are also diﬀerent.

Investigating this question was the goal of the present

experiment.

2. Materials and methods

2.1. Judges

Six judges (age range 20–25 y), female students at Ewha

Womans University, Seoul, South Korea, participated in

the experiment. The judges were requested not to eat or

drink (except water) for at least half an hour before the

tests. All were na¨ve to the speciﬁc aim of the study,

although some of them had participated in psychophysical

experiments before.

2.2. Stimuli

The stimuli consisted of three confusable pairs of diﬀer-

ent low concentration NaCl solutions: 7 and 10 mM, 10 and

13 mM, and 12 and 15 mM. The stimulus pair to be discrim-

inated was not ﬁxed. It was varied randomly over the three

pairs, in order to have judges focus only on the diﬀerences

between the stimuli in the pair and to minimize any learning

eﬀects. For convenience, the stimulus with lower concentra-

tion in each stimulus pair will be denoted as ‘W’ (as the

weaker stimulus) and the stimulus with higher concentra-

tion will be denoted as ‘S’ (stronger stimulus).

The NaCl solutions were prepared by dissolving reagent

grade NaCl (Ducksan Pure Chemical Co., Ltd., Ansan,

Gyeonggido) in deionized water. The NaCl solutions were

dispensed in 10 ml aliquots using Labmax Bottle-Top

Dispensers (Witeg Scientiﬁc, Berlin, Germany), and served

H.-S. Lee, K.-O. Kim / Food Quality and Preference 19 (2008) 97–102

in 2-oz semitransparent plastic cups (Jesam Co., Sungnam,

Gyeonggido). All stimuli were presented at constant room

temperature at 20 ± 2C, on plastic trays, with two duo–

trio tests per tray.

2.4. Statistical analysis

Values of d 0 were computed for each sequence of the

three versions of the duo–trio test from the pooled data

over the six judges, using IFPrograms software, assuming

the comparison of distances cognitive strategy (Institute

for Perception, Richmond, VA). These can also be com-

puted from the proportion of correct responses using tables

( Ennis, 1993 ). Signiﬁcance of the diﬀerences between d 0 val-

ues was tested using chi-square tests (d 0 -test, IFPrograms,

Institute for Perception, Richmond, VA).

2.3. Procedure

Each judge performed three versions of the duo–trio

test. For the ﬁrst protocol, the traditional duo–trio, the ref-

erence stimulus was tasted ﬁrst. On tasting the two test

stimuli judges were required to report which one was the

same as the reference. For the purposes of this article, this

protocol will now be denoted as the ‘DTF’ (Duo–Trio

First). For the second protocol, the ‘DTM’ procedure

was used ( Rousseau et al., 2002 ), while for the third proto-

col, the ‘DTFR’ procedure was used.

For all three protocols, for half of the tests, the higher

concentration NaCl solution was used as the reference

stimulus, while for the other half, the lower concentration

was used. All three pairs of stimuli were used for each pro-

tocol. Thus within a protocol the stimulus pairs were con-

stantly changing. This is called a roving design ( Macmillan

& Creelman, 2005 ). For each pair of stimuli and each pro-

tocol there were four possible sequences of tasting. This

gives a total of 36 possible sequences of tasting (3 stimuli

pairs 3 protocols 4 sequences of tasting). Each judge

performed all 36 sequences once in an experimental session.

The tests were grouped according to the protocol (12 DTFs

followed by 12 DTMs followed by 12 DTFRs). The six

possible orders of protocols were counterbalanced for each

judge. Accordingly each judge performed six experimental

sessions and the order of presentation of the protocols was

counterbalanced over judges. Five minute breaks were

taken between protocols within a session to minimize the

fatigue eﬀects. The experimental sessions were separated

by at least 1 day and no more than 3 days. This gave a

grand total of 216 tests per judge.

One deionized water rinse was taken before each test.

Before tasting the ﬁrst stimulus of the duo–trio test, a pri-

mer stimulus was taken in order to make the NaCl adapt-

ing conditions for the ﬁrst stimulus similar to the second

and the third stimulus in the test and prevent the distorting

eﬀect of the rinsing water on the taste of the ﬁrst stimulus.

The primer presented was always same as the weaker stim-

ulus (W) in the pair of stimuli. Judges were told that this

primer was not part of the test and thus, its sensory char-

acteristics should be ignored.

Judges were required to sip the whole 10 ml of each

stimulus at once and expectorate it. No retasting was

allowed in order to examine memory and sequence eﬀects.

Judges responded verbally, and no feedback was given so

as to minimize learning and strategy change. The experi-

ment was conducted in a one to one interview style. Proto-

col testing lengths lasted 5–11 min, 4–13 min, and 5–15 min

for DTF, DTM, and DTFR, respectively. Total session

lengths from starting testing to brief interview at the end,

lasted 30–50 min.

3. Results

The d 0 values obtained from the three versions of duo–

trio test are given in Table 1 . The DTFR resulted the high-

est d 0 value (2.28) and then the DTF resulted the second

highest d 0 value (1.95) and the DTM (1.72) resulted the

lowest d 0 value (1.72). The diﬀerence in d 0 values between

the DTFR and the DTM was signiﬁcant (p = 0.01), indi-

cating a superior performance of DTFR over DTM.

Values of d 0 were also calculated for each sequence for

each protocol ( Table 2 ). For the DTF and DTFR, the d 0

values for four diﬀerent sequences were not signiﬁcantly

diﬀerent from each other. Yet, for the DTM, there were

diﬀerences in d 0 among the sequences. The test sequences

having the ﬁrst stimulus diﬀerent from the reference –

h WSS i and h SWW i , resulted in a higher d 0 than the

sequences having the ﬁrst stimulus the same as the refer-

ence – h WWS i and h SSW i . Table 3 shows the d 0 values

obtained from the results combined according to whether

the ﬁrst two stimuli were the ‘same’ or ‘diﬀerent’. It indi-

cates a signiﬁcant diﬀerence only between the two diﬀerent

sequences for the DTM (p < 0.001).

Sequence eﬀects were also examined in terms of whether

the reference stimulus was the weaker stimulus (W)or

stronger stimulus (S)( Table 4 ). When the duo–trio test is

considered as a triad, the duo–trio test with a weaker refer-

ence becomes a triad with ‘one stronger, two weaker stim-

uli’: S-odd. The duo–trio with a stronger reference becomes

a triad with ‘one weaker and two stronger stimuli’: W-odd.

For the DTM and the DTFR, there was no signiﬁcant dif-

ference between the tests having diﬀerent reference stimuli.

d 0 Variance of

d 0

DTF 319 1.95 cd 0.017

DTM 303 1.72 c 0.017

DTFR 341 2.28 d 0.019

a d 0 values with diﬀerent superscripts are signiﬁcantly diﬀerent

(p = 0.01).

b DTF = duo–trio with reference tasted ﬁrst, DTM = duo–trio with

reference tasted in the middle, DTFR = duo–trio with reference tasted

ﬁrst as well as at the end as a reminder.

Number of correct responses (out of

432)

Table 1

Number of correct responses and d 0 values obtained for the three duo–trio

protocols a

Protocol b

100

H.-S. Lee, K.-O. Kim / Food Quality and Preference 19 (2008) 97–102

Table 2

d 0 values for each sequence for the three duo–trio protocols a

Protocol b

Reference

stimulus c

Sequence

including

reference

No. of correct

responses

(out of 108)

d 0

Variance

of d 0

The DTF tests with a stronger reference (W-odd) had sig-

niﬁcantly higher d 0 values than the DTF tests with a weaker

reference (S-odd).

4. Discussion

DTF W WWS 74 1.63 d 0.069

WSW 76 1.74 d 0.068

S SWS 84 2.20 d 0.072

SSW 85 2.26 d 0.074

DTM W WWS 71 1.46 e 0.073

WSS 89 2.53 f 0.082

S SWW 78 1.85 ef 0.068

SSW 65 1.13 e 0.090

DTFR W WWSW 87 2.40 g 0.077

WSWW 91 2.69 g 0.088

S SWSS 80 1.96 g 0.069

SSWS 83 2.14 g 0.071

a d 0 values obtained from diﬀerent sequences are not signiﬁcantly dif-

ferent for DTF (p = 0.22) and for DTFR (p = 0.28). For DTM, d 0 values

not sharing the same superscript are signiﬁcantly diﬀerent (p = 0.001).

b DTF = duo–trio with reference tasted ﬁrst, DTM = duo–trio with

reference tasted in the middle, DTFR = duo–trio with reference tasted

ﬁrst as well as at the end as a reminder.

c ‘W’ refers to the lower concentration of NaCl solution and ‘S’ refers to

the higher concentration of NaCl solution in a pair of stimuli.

The secondary goal of the present study was to general-

ize to diﬀerent stimuli the superior performance of DTM

over the traditional duo–trio test (DTF), because the

DTM had both test stimuli adjacent to the reference. An

alternative way of achieving this adjacency was to use a

DTFR design and the primary goal of this study was to

determine its ecacy. In the assessment of these tests, a

roving design was used in order to minimize stimulus learn-

ing from repeated testing, which could have led to cognitive

strategy change. From the results, however, the DTM did

not elicit superior performance to the DTF. The DTFR

elicited superior performance (not always signiﬁcant) to

the DTF and DTM, despite a possible hypothesis that hav-

ing four stimuli might have increased ‘fatigue’ and memory

load. The repeated presentation of reference appeared to

have no ill eﬀects.

Rousseau et al. (2002) found that the DTM yielded sig-

niﬁcantly higher d 0 values than the DTF for discriminating

between two orange ﬂavored beverages with diﬀerent sugar

concentrations. In the present study, the DTF elicited

higher d 0 values albeit non-signiﬁcantly. Examining the

individual sequences ( Table 2 ) only the DTM exhibited

variation in sensitivity. The sequences where the ﬁrst two

stimuli were the same elicited much lower d 0 values and

so reduced the overall sensitivity. This eﬀect could be

explained by a hypothesized response bias whereby there

was a tendency to report confusable stimuli as ‘diﬀerent’.

This would reduce performance for the two sequences

where the initial two stimuli were the same. This was sup-

ported by subjective reports that when performing DTM

judges tended to concentrate on determining whether the

ﬁrst two stimuli were the same or diﬀerent while the third

was merely tasted as a check.

Comparing these data with the results of Rousseau et al.

(2002) , it would have been convenient had they not used

these ‘bad’ sequences. However, these were the only

sequences that they used, so bad sequences do not explain

the diﬀerences between the present study and that of Rous-

seau et al. The two studies used diﬀerent stimuli. It may be

hypothesized that judges would be more familiar with

changes due to sugar concentration in orange ﬂavored

drinks than with the various taste changes due to NaCl

concentration in saline solutions ( Lee & O’Mahony,

2007a ). Further it may be hypothesized that the above

response bias would be less eﬀective with more familiar

stimuli. This might furnish explanation for the diﬀerences

between the two studies.

Having discussed the inferior performance of the DTM

compared with the DTF, it remains to discuss why the

DTFR elicited better performance than the DTF. It can

be hypothesized that should there be doubt regarding

Duo-trio having the ﬁrst

two stimuli, ‘diﬀerent’: h WS i

or h SW i

DTM 1.30 d (0.039) 2.17 e (0.036)

DTF 1.93 c (0.034) 1.96 c (0.034)

DTFR 2.26 f (0.037) 2.30 f (0.037)

a d 0 values obtained from tests with each type of ﬁrst two stimuli (same

pair vs. diﬀerent pair) are signiﬁcantly diﬀerent for DTM (p < 0.001) and

are not signiﬁcantly diﬀerent for DTF (p = 0.91) and DTFR (p = 0.88) for

comparisons within protocols. For comparisons between protocols, d 0

values of the protocols sharing the vertical line are not signiﬁcantly dif-

ferent (p = 0.05).

b DTF = duo–trio with reference tasted ﬁrst, DTM = duo–trio with

reference tasted in the middle, DTFR = duo–trio with reference tasted

ﬁrst as well as at the end as a reminder.

Duo-trio having the ﬁrst

two stimuli, ‘same’: h WW i

or h SS i

Duo-trio with the stronger (S)

reference: W-odd

DTM 1.66 e (0.034) 1.79 e (0.034)

DTF 1.68 c (0.034) 2.23 d (0.036)

DTFR 2.53 f (0.041) 2.05 f (0.035)

a For comparisons within protocols, d 0 values obtained from tests with

each type of reference are signiﬁcantly diﬀerent for DTF (p = 0.04) and are

not signiﬁcantly diﬀerent for DTM (p = 0.62) and DTFR (p = 0.08). For

comparisons between protocols, d 0 values of the protocols sharing the

vertical line are not signiﬁcantly diﬀerent (p = 0.01).

b DTF = duo–trio with reference tasted ﬁrst, DTM = duo–trio with

reference tasted in the middle, DTFR = duo–trio with reference tasted

ﬁrst as well as at the end as a reminder.

Duo-trio with the weaker

(W) reference: S-odd

Table 3

d 0 values (and variance of d 0 values) for tests having each type of ﬁrst two

stimuli for the three duo–trio protocols a

Protocol b

Table 4

d 0 values (and variance of d 0 values) for tests using each type of references

for the three duo–trio protocols a

Protocol b

H.-S. Lee, K.-O. Kim / Food Quality and Preference 19 (2008) 97–102

101

which test stimulus is the same as the reference in the DTF,

the introduction of the ﬁnal reminder stimulus would allow

a second chance for the judgment to be made.

It is interesting that this eﬀect was only apparent when

the weaker stimulus was the reference. From Table 4 ,it

can be seen that for the DTF, the d 0 was smaller when

the reference was the weaker stimulus. Also, the reverse

was the case for the DTFR. Therefore, the diﬀerence

between the DTFR and DTF was enhanced when the ref-

erence was the weaker stimulus. However, these eﬀects

require explanation.

For the DTF, performance was inferior when the refer-

ence was the weaker stimulus. Consider the following

hypotheses for the four sequences of tasting. For the

h W R WS i sequence, adaptation to the reference (W R ) could

cause the ﬁrst test stimulus (W) to appear much weaker

while the second test stimulus (S) weakened by adaptation

might become more similar to ‘W R ’ than ‘W’. For the

h W R SW i sequence, adaptation to the reference (W R ) could

cause the ﬁrst test stimulus (S) to appear weaker. Greater

adaptation eﬀects due to the ﬁrst two stimuli would cause

the third stimulus (W) to appear even weaker and thus less

similar to ‘W R ’.

For the h S R WS i sequence, adaptation to the reference

(S R ) could cause the ﬁrst test stimulus (W) to appear much

weaker. Adaptation to ‘W’ would be likely to be less strong

and aﬀect the third stimulus (S) to a lesser extent. There-

fore, there could be a tendency to judge ‘S R ’ and ‘S’as

more similar. For the h S R SW i sequence, adaptation to

the reference (S R ) could cause the ﬁrst test stimulus (S)

to appear weaker. Greater adaptation eﬀects due to the ﬁrst

two stimuli would cause the third stimulus (W) to appear

even weaker and thus less similar to ‘S R ’.

Considering these four hypotheses, contradictory to the

prediction of Sequential Sensitivity Analysis (SSA), there

would be greater tendency for errors and lower d 0 values

when the reference was the weaker stimulus for the DTF

protocol. Now consider hypotheses for the DTFR

protocol.

The task of the judge was to compare the two test stim-

uli (in the middle of the sequence) to the two reference

stimuli at the beginning and end of the sequence. This task

is made easier if the references both appear to be either

stronger or weaker. It is made more dicult if one refer-

ence appears to be stronger while the other appears to be

weaker. When the reference is the stronger stimulus, the

ﬁrst reference will appear stronger but adaptation from

the stronger stimuli in the test will render the ﬁnal reminder

reference to be weaker. The references would appear to be

diﬀerent and so cause confusion. When the reference is

weaker, the ﬁrst reference would appear weaker and any

adaptation eﬀects will render the ﬁnal reminder reference

to also appear weaker. The two references would appear

to be close enough to be the ‘same’.

These explanations were based on adaptation eﬀects and

speciﬁc to the NaCl/NaCl model system that used in this

study. Using diﬀerent model system or food system would

be expected to give diﬀerent results. Introduction of other

sensory modalities for example trigeminal stimulation

( Carstens et al., 2002 ) would be expected to give still diﬀer-

ent results. Regarding DTF, in fact, some studies reported

the superior performance of the weaker reference (S-odd)

over the stronger reference (W-odd) version of duo–trio

( Mitchell (1956) working with blended whiskies; O’Mah-

ony & Odbert (1985) working with a puriﬁed water/low

concentration NaCl model system) while others reported

no diﬀerence in performance between S-odd and W-odd

( Rousseau et al. (1998) using vanilla ﬂavored yogurts,

Rousseau et al. (2002) using orange ﬂavored drinks).

Many previous studies investigating the diﬀerence test

sensitivity, including the studies that developed the Sequen-

tial Sensitivity Analysis (SSA), used a puriﬁed water/low

concentration NaCl model system ( Dessirier & O’Mahony,

1999; Dessirier, Siﬀermann, & O’Mahony, 1999; Lau et al.,

2004; Lee & O’Mahony, 2007b; Tedja, Nonaka, Ennis, &

O’Mahony, 1994; O’Mahony & Odbert, 1985; O’Mahony,

Thieme, & Goldstein, 1988; Thieme & O’Mahony, 1990 ,

etc.). Yet, water stimuli have contrasting properties when

tasted adjacent to NaCl stimuli ( Lee & O’Mahony,

2007b ) and diﬀerent food stimuli would elicit diﬀerent

extent of adaptation. Therefore, there should be a caution

when these results were generalized to the performance of

diﬀerence tests using diﬀerent, often more complex, food

stimuli.

Acknowledgement

The authors would like to thank Michael O’Mahony for

his helpful comments and advice on the manuscript which

improved its clarity and readability.

References

ASTM (1968). Manual on sensory testing methods. Philadelphia: American

Society for testing and materials.

Carstens, E., Carstens, M. I., Dessirier, J.-M., O’Mahony, M., Simons, C.

T., Sudo, M., et al. (2002). It hurts so good: Oral irritation by spices

and carbonated drinks and the underlying neural mechanisms. Food

Quality and Preferences, 13, 431–443.

Dessirier, J. M., & O’Mahony, M. (1999). Comparison of d 0 values for the

2-AFC (paired comparison) and 3-AFC discrimination methods:

Thurstonian models, sequential sensitivity analysis and power. Food

Quality and Preference, 10, 51–58.

Dessirier, J. M., Siﬀermann, J. M., & O’Mahony, M. (1999). Taste

discrimination by the 3-AFC method: Testing sensitivity predictions

regarding particular tasting sequences based on the sequential sensi-

tivity analysis model. Journal of Sensory Studies, 14, 271–287.

Ennis, D. M. (1993). The power of sensory discrimination methods.

Journal of Sensory Studies, 8, 353–370.

Ennis, D. M., & O’Mahony, M. (1995). Probabilistic models for sequential

taste eﬀects in triadic choice. Journal of Experimental Psychology:

Human Perception and Preference, 5, 1088–1097.

Kim, H.-J., Jeon, S. Y., Kim, K.-O., & O’Mahony, M. (2006). Thursto-

nian models and variance I: Experimental conﬁrmation of cognitive

strategies for diﬀerence tests and eﬀects of perceptual variance. Journal

of Sensory Studies, 21, 465–484.

Difference test sensitivity - Comparison of three versions of the duo-trio method requiring different memory schemes and taste sequences.pdf

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: