Food &lily
PII:
ELSEVIER
s0950-3293(97)00021-9
Vol. 8, No. 5/6, pp. 429-438, 1997 1997 Elsevicr Science Ltd. All righs rexrved Printed in Great Britain 0950-3293/97 Sl7.00 + .Ga
and PrcJmnce
0
TOWARDSCONNECTIONISTMODELSOF FOODCONSUMERAlllTUDES 0. ThieV & Ph. Robert Demontrondb “E.N.I.T.I.A.A., Department SMAD, Rue de la Girauditre BP 82225,44322 Nantes Cedex 03, France $REREG UMR CNRS C6585, University of Rennes I, 11 Rue Jean Ma& BP 1997, 35019 Rennes, France (Accepted 17 May 1997)
the response from the innumerable sensorial stimuli (olfacto-gustato-sensitive and visual) which is created by
ABSTRACT
the contact with food, depends on molecular and then on cellular phenomena which affect neural processes (cf.
This paper is in keeping with a long term research program in the field of marketing and particularly in the study of consumer behaviour. In continuation with the cognitiuist paradigm, a connectionist approach to attitude modelling is proposed and the theoretical and metatheoretical bases of this research are presented. This orientation consists of studying how the recourse to the neural networks should be constituting an interesting and innovative decision support in this field. This research is particularly based on Beckwith and Lehmann’s (1975) model which is inspired by Fishbein’s (1963) linear and additive representation of the attitude concept and Bass and Talarzyk’s (1972) model. It is demonstrated how a basic automata network can improve knowledge of attitude dynamics by showing daTerent attractors (jxed points and limit cycles). This work opens a new research axis in the food marketing area. 0 1997 Elsevier Science Ltd. All rights reserved Keywords: Connectionism; attitude forming; network; food consumer behaviour.
Nicolaidis, 1992). In the final section, a new research program in the food marketing area is proposed.
CONSUMERATTITUDESTO FOODPRODUCTS In food product buying choices, different categories of variables come into play. According to Claudian (1978), the food behaviour factors which correspond to the attributes that we assign to a product perception come from organic,
psychological,
and social origins.
Accord-
ing to Bodenstedt, these factors take into account the food, the consumer, society’s characteristics and the abiotic environment (Bernard et al., 1993). They also depend on the subject’s situation, on their context and finally, on the presentation of the product (cf. Issanchou and Hossenlopp, 1992). Moreover, every subject has its individual story which comes from learning which is conditioned by personal, family, social and cultural experiences (cf. Rozin, 1988; Fischler, 1990). From this complexity, many attempts at rationalisation of the food behaviour have been conducted; see for instance, Rozin and Fallon ( 198 1) who have studied the different reasons for food acceptance or rejection by the consumers. In the following section, the common models which describe attitude formation in mathematical terms are presented.
automata
INTRODUCTION
The work which is presented in this paper is essentially conceptual. In the first section, after a short presentation of previous research focusing on consumer food attitudes, the different types of attributes in the perception of food products by the consumer are stated. In the second section, the usual models of the attitude concept by using a cognitivist approach are presented. These multiattribute models are often used by marketing managers but are static. For this reason, the third section of this paper proposes a dynamic modelling of attitude formation and it is justified in the fourth section by recourse to a connectionist modelling approach. It has often been demonstrated that
USUAL COGNITIVIST MODELS OFATTITUDES FORMING According to Bechtel and Abrahamsen ( 1993)) “the objective of psychological modelling consists in considering empirical data about the behaviour and in 429
430
D. Thiel, Ph. R. Demonfrond
understanding
how
behaviour
actual practice of psychology then in marketing, attitude investigation
is produced”.
attitudes correspond 1935),
whether
goals
of action
modelling
is one
or
whether
on
non-compensatory-
and Bettman,
and Payne,
and
Einhorn,
1970).
In case
attributes
calculation
tive importance sumer
according
(Dawes and Corrigan,
decision
proposals
process
for that
(Edwards,
1954,
which
1977).
1964;
modes,
the
identity
among
different
satisfaction
of the different
where Psi corresponds
to the subjective
probability
for the chosen
of the consumer
C, is linked
this event.
According
berg’s
(1956)
additive
linear representation
here it is a global evaluation
evaluation
aggregation
of the attitude
Vi the utility
to Edwards
one, Fishbein’s
model
approach
that the
given by
and
Rosen-
also rests on an
of the attitude 1963).
The
by local equation
Ej(cj
.
Cj corresponds
5)
to the probability
has, or has not, the attribute weighting (1972)
of this
model,
attribute.
the global
given by a similar
linear
that option
0
j and Vj is the consumer In
Bass
evaluation equation
independently
process models,
duces other dimensions
for attitudes
the process
factors;
intro-
the
role
of the
determinants;
component;
effect. The last effect is particularly as a cognitive
in his critical
such as: the neces-
of non-reasoned
of the motivational
ciology
and
the
the halo
studied in psychoso-
phenomenon.
Wilkie
(1990)
con-
siders that the halo effect takes place when a consumer overvalues
all the characteristics
of a product
likes (see an example of measurement and
and
Talarzyk’s
of each
option
which
is
compensates
for the local evaluations:
A0 = Ek(Pk. Ak,) where Pk corresponds to an appreciation criteria k weighting of the interviewed consumer; while A, and & give the global evaluation and the local evaluation of the option 0 over k, respectively. Fishbein’s model is certainly the most important model. It can currently be considered as a paradigm
Nemeroff,
misunderstanding Schweder,
1995).
which he
of the halo effect in
At the beginning
of the evaluation
is being influenced
measurement
task (Cooper,
and Sweeney
(1973)
information,
For instance,
to measure
which has a great influence the
cognitive
product
results
in marketing.
halo
effect
proposed
distinguish
the cognitive effect
and quantifies
Beckwith
+
In parallel
attitude
process
with Fishbein’s
representation
(influence
by
to
emotion)
perception).
Their
these two effects on the per-
extension
of his first
integration
of membership
and
level
+
the effects of the emotional
ceptual.
norms
logic.
between
The
as a complete
(perception
(emotion
model shows the relationship
a halo
reaction.
on the individual
effect
a
and then
represents
an emotional
perceptual
( 1975)
and
halo effect
For instance,
can be considered
of the consumer
halo
attributes,
from
Lehmann
social
the emotional
who ‘falls in love’ with a product
which
the
( 199 1) tries to show
of these two kinds of halo effects
proposes a method
effect
use
to reduce the
some other more emo-
tional processes may occur. Aurifeille
consumer
Mazis
this type of halo could be called a
halo, but in marketing,
the importance
of
that the individuals
instead of subjective,
Therefore,
1977;
potential
by some aspect of the
1981).
remarked
of the
task (Tversky,
1980). In each case, the cognitive
the evaluator
from where
the person’s self-
behaviour
attitude
part
A, is:
A, =
experi-
review of these different
overvalues
concept-
which is formed
(Fishbein,
by different
also proposes some extensions of the
(1989),
nature
and
of these models
Bagozzi
ambiguity.
. Vi)
i, and
them
used. For
Shepherd
of his or her attitudes”.
cognitive
of the event
and validate
Shepherd
which “may influence
objective
occurrence
and
Stein
by:
option
are commonly 1995)
present some applications
to food choice mentations.
1975),
research, the halo was due either to the ambiguities of the attributes which are used for the evaluation, or to the
gives the higher
uc= Ci(PSi
In the literature
to their subjec1974).
The evaluation
1970).
of the different
models shows the con-
as the choice
options lJ‘ is calculated
(Dawes,
the
and squares with
or estimation
One of the first compensatory
of a fixed
so that
of compensatory
which are weighted
to the
are all greater
threshold,
process is linearly described
a step-by-step
(1994)
goals; the introduction
criteria
definition,
(1988,
sity to introduce
option in question will be finally admitted evaluation
and Ajzen, Shepherd
according
to evaluation,
appreciation
(Fishbein example,
accepted-respec-
or not, that the prominent
a minimum
Bettman,
processes, three types
disjunctive,
proposal which is submitted than
1974;
to Kuhn’s
theory of reasoned action by considering
1985).
models are traditionally
conjunctive
of
of the process which can be
In the case of non-compensatory of non-linear
evaluating
(according
of food choice, it is shown that this model and its variants
Sparks
to action (Allport,
on compensatory
(Nakanishi
1979; Johnson
necessity,
of the
Fundamentally,
to predispositions
based
to the complexity
low or high
tively,
the and
fields which clearly develops the cognitivist
a priori basis of thinking as a calculation.
according
In
and psycho-sociology,
and
of the reference
groups on the individual perceptions), Beckwith and Lehmann’s (1975) model gives for each product which was tested by the consumers, the following relation:
with BP~ = &Ap + vjB;j + t+ forj
= 1 to n (number
of attributes)
43 1
Towards Connectionist Models of Food Consumer Attitudes This algebraic
where
axiomatic
of mental operations,
current
Ap corresponds to the consumer attitude for the product p and Ai the average attitude of the consumers; Bpj indicates the perception of the product p by the attribute j and Bij the average perception of the
forming,
seems to derive from very old work. Since 165 1,
cognition
(more precisely, the expression at that time was
consumers;
ratiocination) is described
o
the
weights
the weight of the average the attitude
attribute
attitude,
j
of the average
Bpj. Finally,
and
y
/?j the importance
for the product p in the perception
vj the importance perception
of the
perception
uo and uj represent
of
the
to notice
interpretation
model. Beckwith
here
of the
and Lehmann
some results
(1975)
Yalch
attributes.
(1976)
Johansson,
contested
it is the predominant
attributes
explains
which
measured
(1991)
tested
applying
some ran-
by
this model
influence
on the
MacLachlan
and
importance
He observed
that, of the
with the halo
and Lehmann.
on the choice
did not reduce
this
Aurifeille
of toothpastes
that the emotional
the ambiguity
for principal
In
the
formation
next
section,
process
a
modelling
of the
in a time-sequential
attitude
process
is pro-
posed.
addition
of the parts”
(Hobbes,
epistkme’, Bentham
by an optimal
management
and displeasures.
is basically
period,
problem) absence trond,
of the representation process
(Bagozzi,
of dynamic
modes
1989;
idea postulated
aspects is observed
1994; Robert-Demontrond
1991),
an
(Robert-Demon-
and Thiel,
ently combined
Bj = Perception
according
1995).
utility differential
the negative
evaluations.
orientates
uf a
to the attribute j
of
the halo effect
all the
attribute;
by
B*l
B*2
consumers
FIG. 1. Sequential process of consumer attitude forming.
B*3
...
Many show
influences research
of pleasures whatever
it
based on the during
a long
‘reason
books’
In the current
models,
the
or not, can be indifferby a summation-
between
of the internal
composition
to addition,
is very much
experiences that
the positive and
the
in psychology order
of
the final result. For instance, of Asch (1946)
and
processing the
which deals with
process of feelings: in his point of view, the of elementary
but come from a first feeling which highly the judgement.
To illustrate Beckwith
called
do not stem from the addition
evaluations,
the attribute j after
ofthe
were
into a global utility,
the greatest
by a consumer
Ry = Perception
of
finally choose the option which lavished
these aims, the process of consumer for a given product
and Lehmann’s
A * = “Average”
product
arithmetic
of a ‘budget’
which form an offer, commercial
tude forming
1995).
an
the
is that the local utilities of the attributes
gestalt original
of the attitude
Aurifeille,
In the
the active and the passive: the
books
(Robert-Demontrond,
the forming
forming
defines
countable-moreover
the account
the attributes
(the
p. 37).
The usefulness of a choice,
positive and the negative, model
psychosociology
about the theme
1651,
slowly impregnates
is, is then given by the result of a calculation
attitudes literature
we
aims at solving the ethical problem by the ‘deontology’, or calculation of the desire satisfaction
open to criticism.
marketing
“when
a total sum by
which
In fact, the identification
On reviewing
process
series of operations,
calculation:
of these ideas which
law of the local evaluations
A SEQUENTIAL ATTITUDE FORMING PROCESS MODEL
of attitude
as recurrent
subtractions-a
the individuals
function.
representations
we do no other than to conceive
pleasure
disagreements given
their sensitivity
by Beckwith
to 78 students.
halo effect
or
continuity
this analysis and suggested
on the contrary, effect
additions
Bpj, and Bij in the
suggested that the
halo effect seems to have an important ambiguous
cognitivist
scientific
is interesting
about
the
reason,
dom differences. It
in
attitude
of
which is derived
model, is represented
attifrom
in Fig. 1.
432
D. Thiel, Ph. R. Demontrond
The consumer attitude regarding the product which is under their evaluation on time t, is defined by A(t) where t is included in a continuous temporal space T which is here discrete, so that Card (T discretized) is equal to n (i.e. the number of attributes of the product). The final consumer attitude (at the end of the evaluation process, i.e. when t is equal to the upper bound of iT) is then given by A(n). In these conditions, the modelling permits the elaboration of the process of A(n) according to different sequences of the attribute process, chosen arbitrarily. Practically, the principle of the modelling consists of a sequentialisation of the attitude forming process by a successive integration of the attributes. The calculation starts then by a first attribute which provides B1, i.e. a local evaluation; then A( 1) by considering the ‘norm’ A’ which corresponds to the ‘average’ consumer opinion for the considered product. The initial value of the attribute 1 given by the consumer is then modified into g1 by a halo effect which is coming from his own attitude A( 1) and from taking consideration of the ‘average’ evaluation B; by the other consumers. The temporal process is then continued by the forming of the attitude A(2) by integration of the second attribute, and so on.... The corresponding algorithm of the dynamic process modelling is the following: (a) Initialisations
of the variables:
n = number of product For j = 1 to n:
attributes
Initial&e: BJ (average perception of the attribute j) Oj (weight given to the attribute j) fij (weight of the attitude A in the halo effect) yj (weight of the ‘average’ perception of the attribute j in the halo effect) End j A* = average attitude of all the consumers y = ‘average’ attitude influence of the individual consumer attitude Calculate: Al = 01 B1 + y A* Calculate: B’, = filAl + y1 B*,
(b) Iterative
Example
1
This example illustrates a non-linear modelling of compensatory processes of attitude forming. A product like a packaged ready-made meal is chosen. Three attributes are chosen by the consumer, for instance (1) the external appearance, (2) the price and (3) the brand of the product (n = 3) *. Different numerical values are given to the levels : (1) of the weights of each attribute; (2) of the local evaluations of the product according to their different attributes; and (3) starting with an initial attitude equal to 0. Six possibilities of sequential attitude forming were then simulated as shown in Fig. 2 (the vertical axis represents the value of the attitude which is standardised by individual according to all the tested products. The attitude is negative in the case of a product buying refusal). The experimental hypotheses are given by Tables 1 and 2. It is possible to observe that the attitude amplitude changes during the sequential forming process and the final values are different in the six cases. The abscissa indicates here the time evolution, i.e. gives the moment (time interval) when each attribute is taken into account to the end of the global evaluation of the product. In our example, n is equal to 3, each evaluation sequence is described during three periods which correspond to the integration of each attribute. As shown, according to the order in which the consumer considers the attributes of a given product, his attitude progressively changes along the time, ending up in very different appreciations (notice particularly the opposition between the sequences S3 and S4 and the sequences S2 and S5; the sequences Sl and S6 are neutral). The non-linear calculations which permit avoidance of the algebraic hypothesis of a composition law of mental representations with commutative and associative proprieties, give then the possibility of a dialectical surpassing the cognitivist and gestalt approaches.
TOWARDSCONNECTIONIST MODELS
loops:
A connectionist DO for t = 2 to n by step 1 S = 0 (initialising the sum) DO for j = 1 to (t-l) S = S + Wj B’j End j At=S+otB,+yA* gj = sj A, + vj B*j
modelling
approach
These previous models are very illustrative of the cognitivist movement: there is often no algebraic difference (syntactic) between the additive models-only semantic differences. In other words, the modelling often seems purely “scholastic”
(Albou,
1980, p. 832): approximately,
END t
the formulations are the same, but the interpretations do not vary more than in a “subtle way” (Dussart, 1983,
The attitude forming is described here as a sequential process. In the following example, the consequences of changing the sequence order of the different criteria during this alternative process, is studied.
*See the work of Cabanac (1992) who demonstrates by experiences that in the strategic food choices which imply a cost, the subjects adjusted quantitatively their behaviour by an algebraic addition of the financial cost and the gustative pleasure.
Towards Connection& Models of Food Consumer Attitudes
FIG. 2. Evolutions of the attitude. TABLE 1. Rank of Each Attribute in the Six Sequences Sl to S6 of Attitude Calculation Sl Attribute 1 Attribute 2 Attribute 3
S2
S3
S4
S5
S6
1
1
2
2 3
3 2
1
2 3 1
3 1 2
3 2
3
1
TABLE 2. Numerical hypotheses 01=1;
y=-1;
ws=l;
/3*=-l;
y,=)$=)+=p,=/.?3=1.
p. 232). Finally, the empirical tests are not very determining: for example, for some models presented previously, experience sometimes gives an advantage for Fishbein’s model over Bass and Talarzyk’s model (Bettman et al., 1975), or sometimes an advantage to Bass and Talarzyk compared to Fishbein’s model. In these conditions, if it is still possible to propose some new developments in this area, it should be possible by the opening of a paradigmatic break. In concrete terms, it seems that just one aspect has to be considered at present in the definition of the attitude concept which was initially proposed by Allport-the definition “princeps” according to the expression of Thomas and Alaphilippe (1983, p. 32) is the foundation of all the different works in this field. The one aspect is that Allport does not restrictively specify the attitude as a mental frame of mind but also characterises it as a neurologic frame of mind. This work begins as early as the origin, a perspective of study of the attitude forming process by the body, and not only by the mind. The reason for the present omission of this approach can be explained by the prevalence of cognitivism in psychology and psychosociology. There is a new movement of ideas resolutely in competition with cognitivism and its compute-symbolic representations: an explosion of works which considers the relations between the body and the mind (Richelle, 1993; Varela et al., 1993; Feltz and Lambert, 1994; Delacour, 1995); a movement of ideas called connectionism (Feldman and Ballard, 1982), which seems to be, according to Schneider (1987)) a paradigmatic revolution within psychology. By using the computer as support for theoretical working representations of the mind, it corresponds, in practice, to the equivalence of the functions
433
between the model and the reality-an analogic equivalence which a priori does not require to consider the structural characteristic of this reality. In concrete terms, this implies a total indifference to the cortical matter. An alternative approach, within cognitivism, tries to naturalise the mind, rejects the idea of the dissociation of the psychology and the neurobiology, and tries to incarnate the spirit in the cerebral tissue (McCulloch and Pitts, 1943). Coming from this “paleo-connectionism” (Varela, 1989) which is still very tinged with themes and problems of the calculation metaphor and of a logical representation of thinking, the connectionism (or neoconnectionism) corresponds to a neurocalculation, on a “neurologic authenticity” (Van Gelder, 1991) of modelling thinking, according to the idea that it is absolutely necessary to consider the particular ways that the cognition is instanced and brings to psychology deep theoretical disruptions. The researcher is motivated to elaborate connectionist models of neuronal type, to reduce the cognitive theories to a level which will be relevant to the neurosciences. “It is undeniable that the analysis level which is adopted by the PTC (proper treatment of connectionism) is lower than those of the traditional symbolic paradigm; but, currently, the level of PTC has more explicit links with the symbolic paradigm as with the neuronal level” (Smolensky, 1988). The common criticism of the cognitivist psychologists against the connectionist models is to say that it is not the network architecture which does the essential work but the way in which the information is coded in the different layers. It is right that in most cases of the connectionist practice, the coding schemes correspond to adaptations of the analysis of the symbolic tradition researchers. In the cognitive sciences area, it is usually assumed that the connectionist models have a neural inspiration and that the units have neuron-like forms. Many researchers who used these terms recognise that their models are not real neural networks. Nevertheless, some surprising similarities exist. For example, the connectionist units and the neurones are elementary computing units which combine inputs coming from certain units and send outputs toward other units. In the connectionist networks and in the neurologic systems, it is the connectivity configuration which seems to be the essential determinant of the behaviour (see the complete analysis of the different theses concerning this subject in Nadel et al. (1989)). Finally, to moderate our position about current connectionist attitude modelling, it is worth citing Clark (1991) who shows that these models are incapable of handling certain sorts of psychological phenomena because they do not encode explicit rules. Nevertheless, the next section tries to show the interesting possibilities of this new approach.
Proposition of a connectionist I n practice, a neural sequential step-by-step
model
network does not evolve by calculations, but its trajectory
434
D. Thiel, Ph. R. Demontrond
corresponds to a dynamic system, although the equations are often discretized for the simulations. To progress from cognitivism to connectionism, we change from an interpretation of the cognition facts and phenomena which initially concern the logic (of the discontinuum), to an interpretation concerning the dynamic and the topologic (of the continuum). We present an automata network (cf. McCulloch and Pitts, 1943) of Beckwith and Lehmann’s model which can be represented by a connection graph. The particularities of an automata network is that it may be defined, in a general way, as a (large) set of cells (finite automata), locally interconnected, which can evolve at discrete time steps through mutual interactions. Formally, an automata network can be described as a mapping F from S” into itself, where S is a finite space (state space). The network is then made up of n interconnected cells. The connection structure is defined by F: cell i receives a connection from j if Fi depends on the jth variable (where F; is the ith component of mapping F). A state of the network is a vector x in S”. A dynamic network is then defined through a rule that transforms any vector x in s” on the network into a vectory in S”. For example, the parallel iteration rule is defined as: y = F(x) and can be interpreted as follows: at each time step, each automaton computes its next state by using its mapping Fi on the current state x. As the state space S is usually finite, all trajectories will be periodic, limit cycles or fixed points. In our research, Beckwith and Lehmann’s model is represented by a network where the automata correspond to the different variables A, A*, Bj and Bj. The connections between the different automata have the following weights: wj, fij and Y. This network was constructed according to the causality relationships between (Bj, A’) + A and (A, BJ) -+ Bj (see also similar work in Thiel, 1995a,6). Figure 3 shows the principle of the structure of this automata (or neural) network. To demonstrate the didactic and heuristic interest of this model, a simple example is presented. At a later stage, this type of model will be scientifically validated by comparison with real situations. In relation with this network modelling approach, Grunert ( 1996) proposes a network of the purchase-relevant cognitive structures with links between four aspects which are product types,
product uses, product alternatives and product attributes. In our opinion, the associations between elements could also be modelled by a connectionist network. Another point which could be criticised in our model, is the lack of the prior knowledge. For instance, in a monadic test (sequential), O’Mahony and Goldstein (1986) have shown some phenomena due to the adaptation and the memory. An alternative of this absence of prior knowledge could be, for example, to complete Beckwith and Lehmann’s model by particular automata which represent the ‘memory’ of the different attributes perceptions and also the prior attitude toward the product. Another advantage of a neural network model is that it is able to represent the memory which is accessible by its contents.
Example 2 By taking the case of an attribute state reduced to only three elements, the different vertices of the graph are transformed into automata and the arrows into connections between the automata (as shown in Fig. 3). The valuations of these arrows correspond to the connection weights of a scale which range through -3 to +3 (semantic differentiator going from ‘a little influence’ to ‘very influential’: -3, -2, -1, t-1, +2, +3). These values correspond to the values on the graph arrows (see Fig. 4).
(a) Model variables + nl, np and ng correspond to the product attribute values of appearance, price level and brand given by the consumers, respectively indexed 1, 2 and 3. The values used were 0 to 3, depending on whether the attribute valuation was reject (0); or neutral (1); or moderately attractive (2); or finally very attractive (3). + ns corresponds to the consumer attitude which emerges from the network dynamics. Three situations are formulated: the value 0 indicates no intention of purchasing a product through rejection; the value 1 indicates no intention of purchasing a product by indifference or by hesitation; the value 2 indicates the intention of buying the product.
Average Affifude
“’ \’
A’ Average Attitude
\y
1
*z/jf$2Bn<; Atrribure I
B2 Amibule
Bl
B'll
2
k y2
FIG.
3. Equivalent
Lehmann’s
model.
automata
network
n4
B-2
of
u
APPEARANCE
nI
-A+;HcE‘“6 1
‘I n4, n5. n6 = avemge
Beckwith
values
for the three dlflerent ottnbures
and
FlG.4.
Example
of an automata
network
implementation.
Towards Connection& Models of Food Consumer Attitudes
(b) Model constants +
n.+, n5 and TV correspond to the ‘average’ attribute appreciations which can be either unfavourable (0), or favourable (1). In our example, the retained values are all equal to 1, which coincide with the attributes which were considered attractive by the consumers. + n7 corresponds to the consumer ‘average’ attitude towards the product, which has the values 0 (for a rejection attitude) or 1 (for a positive attitude). The value 1 is arbitrarily retained for the simulation. The automata
activation
If (ns+ns-l)
> 0
If (ns--n*+
1) > 0
If (ns+ns-1) ?4=n5=7i6=
rules and threshold
functions
> 0
are: else nt = 0
then nt =ns+ns-I then ns = ns -na + 1
else n2 = 0
then ns=ns+ns-1
else ns = 0
1
here considered as moderately attractive while the price is considered at a reject compensation and considering other (the ‘social norms’), the final attitude product purchasing intention (ns = 2).
Neurons
(0 0) (3) (4) (5) (6) (7) (8) 020
11110
+ Fixed point attractor: (1) (2) (3) (4) (5) (6) (7) (8) 11111111
> 0 th en ns=n7+nt-nq+ns-1
States
In case the appearance and the brand perception turn out to be unimportant for the consumer and attribute 2 (np, the price) is moderately attractive, the final attitude corresponds to an absence of intention to purchase the product-by refusing (n8 = 0).
Neurons
States
else ns=O
This network has enabled explanation of some dynamic proprieties of the attitude forming process-especially stationary (fixed points) and periodic (limit cycles) attractors (the software MUMPS was loaned by Professor Atlan of the Hebraic University of Jerusalem).
Analysis of the observed attractors Our automata network is a deterministic system. Therefore, if the network goes a second time on a previous configuration, the sequence of the different states remains the same as after the first one and the system describes indefinitely a loop in the state space. These different loops correspond to the attractors of the dynamic system and the moving time of the loop, on the attractor period. If this period is equal to one, then a fixed point can be observed. The limit cycles can also be observed if this period is greater than 1. The whole of the configurations which evolve toward a given attractor correspond to an attractor basin. The simulations results of our previous model are described in the following section.
Preliminary
by the consumer, level (q = 0). By decision criteria corresponds to a
+ Fixed point attractor:
n, = 1 IIf (n7+nt-ng+ns-1)
435
remark
According to our hypotheses, the states of the neurones (automata) n4, n5, n6 and n7 are invariant. The consequences are first, to consider that the consumers find on average the different product attributes attractive (n4, n5, ng = 1) and second, to consider that the average consumer attitude faced with the product is positive (n7 = 1).
Here the consumer is not particularly attracted towards the different product attributes which are individually considered (neutrality of the states nl , n2 and n3 equal to 1). Contrarily, the fact that the other consumers consider the different attributes as attractive does not change the individual appreciation: finally, it shows an absence of purchase intention without the intention to refuse the product (ng = 1). 3 Limit cycle attractor
length 2:
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(1) (2) (31 (4) (5) (6) (7) (8)
In this circumstance, the appearance of a long term stable behaviour which oscillates between the refusing and the indifference attitudes (or neutral), is observed. After a certain time of the evaluation process, the consumer goes towards a neutral personal appreciation situation of the different product attributes (nl = n:, = n3 = 1) which is in contradiction with the right and contextual evaluation. While the social norm is positive (n7 = 1), the consumer intention is first negative (absence of purchasing intention by refusing: n8 = 0). The achieved state is then unstable: the consumer goes over from a neutral appreciation situation to a reconsidering of the local evaluation (n1 = 0; n2 = 2; n3 = 0 corresponding to a moderate evaluation on price but a reject on brand and appearance). This situation is also unstable (dissatisfaction) in that the trajectory of the neurocalculating does not end in a fixed point (a firm, resolute attitude) but in a limit cycle (an oscillating and undecided attitude).
3 Fixed point attractor: Neurons
(I) (2) (3) (4) W (6) r/ L202
11112
j Limit cycle attractor
(8/
1 States
The attributes 1 and 3 (nl and n3, respectively, appearance and the brand perception of the product)
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the are
(0 (2) (3) (4) (-9 (6) (7) (8) States
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In this case, during the product evaluation process, a positive appreciation situation of two attributes but without purchase intention (n8 = l), is shown. In other terms, it seems like the application of a disjunctive rule which refuses the product because one of the evaluation criteria-here, number 2-is negatively perceived. This state is not the final one: on the next stage the consumer moves towards a positive attitude (ns ~2) which comes, simultaneously, from a depreciation of criteria 1 and 3 (ni = n3 = 1) and from a new appreciation of criterion 2 (nq = 1). This operation corresponds to the affective halo effect where the global attitude (ns) constrains the local evaluations (nl, n2 and ns)-with a review of these last ones when their aggregation gives as an (intermediary) result an evaluation which is opposite to the aimed impression. The state n8 (equals to 2) plays here the role of a final cause in the evaluation process. The situation is here unstable and the consumer oscillates between a neutral and a positive attitude in purchasing intention. Of course, the interpretation of the observed dynamics is not exclusive to other possibilities. Here are the didactic and heuristic interests of our automata simulation approach.
CONCLUSIONS Mindful of the potential reactions of some readers of his paper, Smith (1996) shows the possibilities of connectionist models to make predictions for social psychological variables such as beliefs, attitudes, social judgements and behaviours. Nevertheless, it is also important to recognise that “the advent of connectionist models would not be a revolution so much as a continuation of an ongoing transition from static to dynamic conceptions of mind” (cf. Kruglansfi in Smith, 1996, p. 908).
Proposition of a new research program in the food marketing area The first difficulty in putting these research results into practice will consist of rationally explaining which attributes are perceived important by the consumer for a given product and to quantify their respective weights. Many works such as those of Booth (1981), Wooley (1976) and Kostler (1981), have suggested observing the consumer behaviour in natural situations instead of making tests in the laboratory, but many studies have demonstrated that this method is difficult to implement. For the last 10 years, a lot of work has focused on the study of food choice and on the factors which contribute to its determinism. It is also usually assumed that the number of beliefs or attributes consumers use when forming an evaluation or attitude is limited (see for instance Grtinert, 1996). The problem is then to be able to define and to measure these attributes and weights which are taken into consideration during food choice. Different works concerning the measurement of food
preferences have been recently presented; these papers are not developed here (see for instance, MacFie and Thomson, 1994 or AIR-CAT project, 1995, 1996). In spite of the poorness of current rational knowledge of the human attitudes, it is nevertheless possible to demonstrate that the neuromimetic models are very robust. Scientific demonstrations have shown that in some cases, even after damage to neural networks in the human brain, the behaviour does not change (see Hopfield, 1982; Weisbuch, 1985). It is on this basis that we conclude that even incomplete connectionist models may accurately model behaviour. In operational terms, the marketing manager may gauge the different attribute weights by changing some elements of the mix with the objective of bringing the consumers nearer to the important attractors.
The theoretical and educational interests of this research Whereas the cognitivist models systematically give a stable attitude, the connectionist models furnish the possibility to take into account the periodic solution cases. These cases are not purely idealist or conceptual, but are empirically observed (by observation and by experimentation) and can be linked to Lewin’s original topologic research (1975) which deals with psychological conflict situations which depend on the equality of a ‘goal gradient’ in peoples ways of life. By integration of these data, the connectionist models give the opportunity of a dialectical that surpasses those ofcognitivism and gestalt psychology. The educational interest of the connectionist simulation lies in the diversity of the possible interpretations of an observed trajectory: thus, for the last example, an explanation of the existence of a second-order limit cycle can consist of a contradiction between the personal local evaluations and the social evaluations: these act as standards and, consequently, bring the consumer to a local and global change of appreciations (of the attributes and the product), thus explaining the loop. Finally, the first objective of our connectionist modelling was to improve the knowledge of the food choice mechanisms and particularly of the stability notion during the attitudes forming and transforming. Therefore our proposal is firstly conceptual.
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