Four experiments were carried out in order to investigate the underlying
processes that make up evaluative conditioning. Experiment 1 demonstrated
that Levey and Martin's conclusions regarding the non-effect of stimulus-presentation-order
does not hold true when tested in a methodologically sound environment.
In experiment 2, Levey and Martin's theory is again brought into question
by evidence contradicting the importance of CS-UCS pair similarity. Experiment
3 showed that latent inhibition, and by that classical conditioning, can
and does occur within an evaluative conditioning procedure. In experiment
4, it was observed that evaluative conditioning can create results (attention
allocation) beyond the scope of Pavlovian classical conditioning's explanations,
suggesting the validity of a multiple learning systems approach to evaluative
conditioning. Collectively, these experiments are used to raise questions
regarding possible explanations of evaluative conditioning effects, as
well as to confront some possible methodological issues evident in past
research.
Evaluative conditioning is a phenomenon by which the mere presentation of an affectivly neutral stimuli alongside a liked or disliked stimulus can significantly change ones perceptions of the neutral stimuli in either a positive or negative direction (Hammerl & Grabitz, 1993). The potential benefits of utilizing such a phenomenon, as it is with most conditioning processes, are endless. However, it would appear that the focus of evaluative conditioning techniques now lies in the realm of marketing and advertisement. The examples of such techniques are countless, how often have we seen supermodels used to sell make-up, clothing, or beverages? Most likely one has experience such conditioning hundreds of times.
Evaluative conditioning does work. There is absolutely no doubt about that. What processes underlie the evaluative conditioning procedure is far less understood, and largely a topic of debate. The procedural similarities between evaluative and classical conditioning are clear. Many believe that this is the answer, that evaluative and classical conditioning are one in the same. However, two scientists came forward with a theory regarding evaluative conditioning that threw the classical conditioning stance into question. Levey and Martin (1978) and Martin and Levey (1987) suggested that evaluative conditioning and classical conditioning were completely unique. Their claims were supported by a number of their own findings that presented numerous components of the evaluative conditioning process that could not be explained, or produced by, a classical conditioning approach. First, they noted that the extent to which subjects were conditioned by evaluative techniques was not dependent on the direction of the conditioning. That is, no matter what order the conditioned stimulus (CS) and unconditioned stimulus (UCS) were presented in, evaluative conditioning would occur. Secondly, the scientists sated that the effectiveness of evaluative conditioning is directly related to the perceptual similarity between the CS and UCS, an example of this would be, the hindered or abolished conditioning effects of a CS-UCS pairing that are extremely dissimilar.
Though one might assume from Levey and Martin's work that evaluative conditioning is now a well understood process, recent evidence forces us to reconsider their work, along with past classical conditioning theories, and the new all-encompassing theories. The purpose of this paper is to reconsider these facts, and to make any relevant conclusions regarding evaluative conditioning's inner workings. Experiment 1 questions the validity of Levey and Martin's experiments, and secondly their conclusions, regarding the order of stimulus presentation (Hammerl & Grabitz, 1993). Martin and Levey's second statement, regarding the effects of CS-UCS pair similarity are reconsidered in experiment 2 (Baeyens, Eelen, Van den Bergh, 1989). Now that Levey and Martin's work has been questioned, the probability of a classical conditioning view has been reconsidered. Experiment 3 looks for evidence of one of classical conditioning's components, in the case, particularly the occurrence of latent inhibition (Stuart, Shimp, & Engle, 1987). Experiment 4 looks at the possibility that classical conditioning is nothing other then a single component of evaluative conditioning, which is considered to be a massive multi-component learning system (Janiszewski & Warlop, 1993).
Levey and Martin (1975) theorize that evaluative conditioning is effective when used as both a forward and backward conditioning process. An effect that is not seen in human classical conditioning. More recent experiments suggest that this aspect of Levey and Martin's hypothesis may hold true to a certain extent. Where that, both methods of conditioning produce significant effects, however, the level of conditioning is higher in the forward conditioning method (Stuart, Shimp, & Engle, 1987). Hammerl and Grabitz (1993) have methodological concerns regarding such forward-backward conditioning experiments. They note that, the standard procedure in evaluative conditioning experiments is based upon a within-subject design, where each subject is exposed to both the forward and backward conditioning styles. The authors suggest that the less significant backward conditioning effect may be the result of a confounding factor, like practice effects, that may have been brought out by methodological oversights. Experiment 1 was carried out in order to determine whether forward and backward pairings will both provide conditioning effects when they are presented independently of each other in a between subjects design. The authors expect that the two independent variables (forward and backward conditioning) will provide significantly different levels of subject attitudes (the dependent variable) towards the conditioned stimuli. An effect of conditioning is expected to be seen with the forward conditioning procedure, but not the backwards method.
Participants
Twenty-two subjects (11 females and 11 males) were recruited as unpaid participants from majors other then psychology. Participants ages ranged from 20 to 29 years.
Apparatus
Stimuli pairings. The stimulus materials were 48 colour prints of outdoor sculptures from public places and parks. In order to determine the extent to which subjects "liked" or "disliked" each stimulus they were presented with a cover story, stating the purpose of the study was to examine the influence of sculptures on the attractiveness of cities. Participants were instructed to rate each print by indicating a position on a 21-point scale. The scale was labeled -10, -9, ... , 0, ... , +9, +10. In addition the scale was labeled "disliked" on the left side and "liked" at the right. The two pictures that each subject most liked were used as the liked (L) stimuli, with the only restriction being that at least a rating of +5 had been obtained. Pictures from categories -1, 0, +1 were selected as the neutral (N) stimuli. Pairings were then made for forward (N-L), backward (L-N), and neutral (N-N) conditions.
Procedure
Subjects were randomly assigned to one of the two conditions, forward or backwards conditioning (the independent variables), with the exception of gender being balanced across the groups. Each participant was exposed individually to four different stimulus pairs. Subjects in the first condition (forwards) were shown two N-L pairs and two N-N pairs. In condition two, subjects were exposed to two L-N pairs (backwards) and two N-N pairs. The order of pair presentation was completely randomized, with each stimulus being displayed for 3 s with a 5 s inter-stimulus interval.
Following the presentation of all stimulus pairs subjects then rated the extent to which they liked each print on the scale previously described (the dependent variable). In order to eliminate one possible confounding variable, subjects were questioned in order to determine their awareness of the contingencies between the presented stimuli.
Two subjects were eliminated from experimental analysis, one from each of the two
conditions, because their initial stimulus print ratings did not meet the criterion for "liked" stimuli. Mann-Whitney U tests were used to compare the equality of the two groups prior to experimentation. Using a rejection level of p > .05, no statistically significant differences were found between the two groups.
As for the main purpose of this experiment, the subjects in the forward conditioning group showed significantly higher ratings than those subjects in the backwards conditioning group. For the forward condition (the independent variable) statistical analysis was completed via a Wilcoxon signed-ranks test, which revealed a significantly higher "liked" rating (the dependent variable) for stimuli paired with liked stimuli, when compared to those stimuli in the same condition that had been paired with the neutral control stimuli. At the second level of the independent variable, the backwards conditioning group, no significant differences were found between the ratings of stimuli paired with liked stimuli and those that had been paired with neutral ones.
These results confirm Hammerl and Grobitz's (1993) concerns about the confounding methodology used in past evaluative conditioning experiments. The data also disagrees with Levey and Martin's (1975) statement that evaluative conditioning cannot be a form of classical conditioning, because conditioning occurs with both forward and backward methods, appears to be false. As the data here suggests, upon studying their statement with methods of high rigor, backwards conditioning does not appear to be effective. And thereby classical conditioning could possibly be the process behind evaluative conditioning.
Experiment 2, looks at another one of Levey and Martin's statements regarding evaluative conditioning. That is, that, evaluative conditioning is unique from classical conditioning because similarity and dissimilarity play a factor in the effectiveness of conditioning, an idea that is not supported by Pavlovian classical conditioning.
With Levey and Martin's (1975) hypothesis regarding the uniqueness of evaluative
conditioning being based in part upon their experimental data regarding forward and backward conditioning effects, which have now been shown to be false when replicated in a highly rigid scientific environment (experiment 1), one should, to an extent, be concerned with their additional "evidence" of evaluative conditioning's uniqueness from classical conditioning.
Martin and Levey (1978) stated that the perceptual (dis)similarity between the CS and UCS in evaluative conditioning is a key determinant of the effectiveness of learning and stimulus affect transfer. In their experiments CS and UCS stimuli were both of a visual modality (art reproductions). They noted that evaluative conditioning occurred when the CS and UCS were similar, but, such effects were markedly impaired or absent when the CS and UCS were selected so that they would be explicitly dissimilar.
However, it has been repeatedly demonstrated that evaluative conditioning is possible when dissimilar stimuli or modalities are used. Faw and Parker (1972) showed affect transfer, and thereby evaluative learning, between nonsense syllables and the presentation of an attractive nude or the subjects arm being immersed in ice water. Eifert, Craill, Carey, and O'Conner (1988) provided similar data between positive or negatively evaluated music (UCS) and previously neutral Greek letters (CS).
When considering these diverging results, three thoughts deserve attention. First, perceptual (dis)similarity can be related to modality (e.g., visual or audio stimuli) or to the sub-modality (e.g., colour and form of the visual stimuli). It at least seems unwarranted to accept that CS-UCS (dis)similarity at the modality level necessarily parallels sub-modality (dis)similarity. Second, the inconclusive meta-analysis of relevant data regarding the possibility of evaluative conditioning under conditions of CS-UCS dissimilarity may be directly related to the UCS's quantitative characteristics. One can assume that immersion of a subject's arm into ice water must evoke a much stronger emotional response than the presentation of disliked artwork, and thereby may compensate for CS-UCS dissimilarity. Third, all previous studies have lacked the methodological rigor of today's evaluative conditioning experiments. The previous studies have in part created the aforementioned discrepancies and thereby prevented any accurate conclusions regarding the theoretical components of evaluative conditioning.
In experiment 2 a more completed and valid design has been used to assess the effects of stimuli similarity and dissimilarity on evaluative conditioning. In this design, both the similar and dissimilar pairs consist of exactly the same type of stimuli, and thereby do not differ on a modality or sub-modality level. Consequently, any observed difference in effectiveness of evaluative conditioning (the dependent variable) can be attributed to the similarity/dissimilarity factor (the independent variable). Due to the scarcity of scientifically valid data it is difficult to propose a hypothesis regarding this experiment. However, considering past experimentation and what we perceive as their confounding factors, we expect that perceptual similarity will enhance evaluative conditioning, where as perceptual dissimilarity will impair or abolish the conditioning effect.
Participants
Twenty undergraduate students from the psychology and educational science participated as partial fulfillment of course requirements. Each subject was tested individually and remained uniformed, at that time, as to the purpose of the experiment.
Apparatus
Stimuli. In all conditions seventy colour slides and identical pictures of human faces were used. The faces included a variety of individuals differing in age, gender, size of faces, and colour palette. In addition to the faces, seventy colour pictures and identical slides of contemporary works of art were used as stimuli materials. The art pictures and slides consisted of reproductions of non-figural paintings from Spanish contemporary artists. For the experiment, pairings of a face and art picture represented the dissimilar condition. Whether the UCS stimuli was liked or disliked was determined in the latter mentioned baseline-phase procedure.
Procedure
Baseline phase. To minimize the possibility of demand effects, subjects were given a written cover story. It essentially stated that "we were studying the relationship between subjective evaluation of and psychophysiological responding to stimuli, and this in normal as well as in depressive subjects." It was further stated that this data would be compared to skin conductance responses that would be measured via electrodes attached to the subject.
In order to determine subjects' ratings of "liking," each stimulus was individually presented to each subject, whom, in turn, rated it on a "liking" scale. The scales categories had subscripts of -100, -90, ... , 0, ... , +90, +100 (-100 = very disliked, 0 = neutral, +100 = very liked). Subjects were persuaded to rely on their first, immediate, and spontaneous reactions toward the stimuli. The two face pictures rated the highest were used as each subjects liked (L) stimuli, and consequently the two lowest rated faces became the disliked (D) stimuli. Stimuli from the categories -20, -10, 0, +10, and +20, were used as the subjects neutral stimuli. Stimuli selection for the art slides was acquired via the same procedure.
In order to prepare for the experimental phase, and to remain consistent with the cover story, the experimenter then attached the skin conductance rating electrodes to the subjects. Meanwhile, he arranged 6 CS-UCS stimuli pairings for each the similar and dissimilar independent variable conditions: two neutral-liked (N-L) pairs, two neutral-disliked (N-D) pairs, and two neutral-neutral (N-N) pairs.
Conditioning phase. Subjects were told that we would be starting the skin conductance ratings, and that all they had to do was to watch the projected slides. Stimuli pair presentation was semi-randomized so that no more than two consecutive trials consisted of stimulus pairs of the same type. A different random sequence was used for each subject. Each stimulus pair was presented ten times, for a 1 s duration and with a fixed 4 s inter-stimulus interval. Once the stimulus pair presentations (the independent variables) were presented the experimenter returned to the subjects room. At this time, the subject's evaluative responses (the dependent variable) were reassessed on the very (dis)liked scale previously used in the baseline phase.
A second experimental procedure, not relevant to this summary, was involved in this single investigation. However, this second procedure, regarding a signal learning theory of conditioning, did not involve, or interact with, the (dis)similarity evaluative conditioning analysis, and was thereby excluded from this summary.
As all evaluative conditioning theories would expect, neutral stimuli (CS) took on the affective evaluation of their paired (UCS) stimuli, to a statistically significant extent, when both the CS and UCS were perceptually similar. Neutral stimuli paired with disliked stimuli became less liked, while neutral stimuli paired with liked stimuli receive more favorable evaluations. Finally, neutral stimuli paired with a neutral UCS did not significantly alter in their evaluative ratings.
Contrary to our expectations, as well as those brought forward by Levey and Martin (1987), the above findings for the similarity condition of the independent variable were identical to those for the dissimilarity condition. We were in fact unable to observe any significant first-, second-, or third-order interactions involving the independent variable (the similarity factor), upon the evaluative ratings of the neutral conditioned stimuli (the dependent variable).
These findings are in concordance with the aforementioned studies demonstrating successful evaluative conditioning with perceptually dissimilar stimuli of different sensory modalities. The data, however, creates a second significant blow to the theories of Martin and Levey, which held that evaluative conditioning is uniquely different from classical conditioning because of its observable effects of CS-UCS perceptual similarity/dissimilarity and the significant conditioning that occurs with both forward and backward conditioning processes.
With Levey and Martin's theories, regarding evaluative conditioning's uniqueness, becoming highly questionable, we must reassess the possibility that the evaluative conditioning process simply is a form of classical conditioning. Experiment 3 pursues this possibility by investigating the occurrence of one of classical conditioning's well-understood components, latent inhibition.
Experiments 1 and 2 have brought Levey and Martin's theory, that evaluative conditioning is a separate entity from classical conditioning, into question. With most of their evidence now being de-constructed by studies with higher methodological rigor, it is time to reconsider evaluative conditioning as simply a form of classical conditioning. The experiments used to contradict Levey and Martin's theory has provided two areas of evidence for a classical conditioning explanation of the evaluative conditioning process. The fact that CS-UCS (dis)similarity is irrelevant in evaluative conditioning, and that the direction of conditioning (forward vs. backwards) is a relevant factor, is consistent with a classical conditioning perspective.
Experiment 3 looks for additional evidence of a classical conditioning component, that, if present, would further suggest that "classical conditioning" is indeed occurring. This component is "latent inhibition," an effect that retards the strength of classical conditioning when subjects have been pre-exposed to the conditioned stimulus (CS) (e.g., the advertised brand) independent of the unconditioned stimulus (UCS). Past experimentation has continually demonstrated that subjects familiarized to the CS through pre-exposure will show retarded learning (Lubow, 1973; Lubow, Markam, & Allen, 1968). However, no such demonstration has appeared in an evaluative conditioning or consumer behaviour context. Based on previous experimental data the authors hypothesize that subjects who receive exposure to the neutral CS brand (the independent variable), prior to any conditioning between the CS and UCS, will exhibit less positive attitudes (the dependent variable) towards the brand when compared to subjects from the second level of the independent variable, subjects whom had not received previous exposure.
Participants
Two hundred and sixty undergraduates from business and psychology programs were placed into small group laboratory sessions of at least twenty-five subjects each. Experimental and control groups were randomly assigned to morning, afternoon, and evening sessions.
Procedure
Subjects had been placed into one of five groups. Group one and two were the two levels of the independent variable. Group one was to be exposed to a latent inhibition procedure prior to conditioning, while group two receives no such experience. Groups three, four and five were simply experimental control groups, created in order to identify, and eliminate, the presence of any extraneous variables. Each group was further subdivided into two subgroups, subgroups A would receive a single conditioning trial, while subgroup B received ten conditioning trials. This division was created in order to determine the extent to which latent inhibition may retard the effectiveness of conditioning (the dependent variable).
Upon arrival subjects were greeted and seated in front of a projection screen. Subjects were informed that they were participating in advertising research. Firstly, the group one subjects, the latent inhibition condition, were exposed to a number of five second presentations of the CS, in the absence of any CS-UCS pairing. This pre-exposure also included three randomly ordered products to be used as filler material during the conditioning trials. The remainder of procedures, the conditioning trials, were identical across the subgroup's divisions.
Each trial employed a short delay conditioning procedure with a three-slide sequence: (1) a five second presentation of the CS (Brand L Toothpaste), (2) followed by a five-second presentation of the UCS (one of four pleasant scenes), and (3) ending with a five-second presentation of the CS superimposed on the UCS. The screen was darkened between each 15-second trial for two seconds.
With each conditioning trial a presentation of 15-seconds of filler material was included. The filler material was identical in design to the conditioning trials, but used three other fictitious brands (Brand R Cola, Brand M Laundry Detergent, and Brand J Soap) which were paired with effectively neutral pictures. The filler material was used and randomly ordered with the conditioning material for two reasons. Firstly, filler material was used to detract attention from the CS-UCS presentation and thereby decrease hypothesis guessing. Secondly, filler material minimized any possible temporal conditioning, an effect where UCS presented in a fixed position without other stimulus are automatically conditioned.
For the 10-trial condition, questionnaires were completed following the first of three approximately equal portions of the slide presentation. This was necessary to maintain subject interest and remove a boredom-effect on conditioning that pilot studies had revealed. The questionnaires also acted as the dependent variable measure, by recording the attitudes towards the conditioned brand. The attitude towards the filler brands were also measured in order to detract attention from the experimental Brand L Toothpaste. For the 1-trial condition all measures were obtained following the entire presentation.
In the 1-trial study the results supported our hypothesis. Subjects pre-exposed to the CS showed significantly weaker conditioned responses when compared to those that had not been pre-exposed to the Brand L Toothpaste. The 10-trial condition provided further, and stronger, evidence of latent inhibition, with results identical to the 1-trial condition, even after the considerably lengthened period of CS-UCS conditioning that had occurred.
As the data suggests the development of a conditioned response (the dependent variable) is significantly retarded, at both a 1 and 10-trial level, following previous exposure to the conditioned stimuli (the independent variable). These results can be interpreted as evidence of latent inhibition, and thereby suggests that classical conditioning is at least a component of the evaluative conditioning process.
This experiment also went beyond its primary purpose, providing additional evidence for a classical conditioning process. Data shows that in both the latent inhibition and conditioning groups the 10-trial level created more positive evaluations of the conditioned brand when compared to the 1-trial condition. This conditioning effect is a commonly displayed pattern in classical conditioning experiments. As well, evaluations of the latent inhibition and conditioned Brand L Toothpaste were both more positive then the evaluations of the filler brands, which did not follow any particular classical conditioning procedure.
These results, along with the negative findings in experiments 1 and 2, imply that a conclusion that evaluative conditioning is simply a form of classical conditioning is valid, and that at least, it appears not be as unique a process as Levey and Matin suggested. Experiment four, however, provides suggestive evidence that evaluative conditioning can create effects beyond the typical affect-transfer process that has been explained by classical conditioning.
To this point consumer research involving conditioning techniques has focused primarily on the transfer of affective responses. Other effects of comparable importance, such as how conditioning procedures can influence attention, force us to re-evaluative our views. To fully appreciate how evaluative conditioning may encourage attention, and affective responses simultaneously, we must abandon the view of evaluative-classical conditioning as a single process. As a process conditioning is theoretically limited to explaining learning as an affect transfer between a UCS and CS. Thus, if multiple learning responses are shown to be the result of evaluative conditioning there must be multiple transfers occurring, an idea at odds with Pavlovian explanations of conditioning. This hypothesis, regarding evaluative conditioning procedures, does not eliminate any possible role of classical conditioning. If supported by experimental evidence, evaluative conditioning may in fact be a complex procedure, by which one of its active components is classical conditioning.
Experiment 4 investigates allocation of subject attention as one possible example of evaluative conditioning systems that go beyond the simple classical conditioning procedures. In this experiment, whether or not the independent variable (T.V. commercials) can significantly alter product attention allocation (the dependent variable) is investigated. The authors hypothesized that the commercial organized in a conditioning sequence would encourage subjects to attend to the previously neutral product sooner.
Participants
Fifty-four undergraduate juniors and seniors enrolled in a senior consumer behaviour course participated. All testing was completed eight weeks prior to class discussion on conditioning literature.
Procedure
Subjects were randomly assigned to two stimulus presentation conditions. Subjects individually were brought into a private room containing a television and VCR. They were then given instructions regarding the experiment. Subjects were told that in this first experiment they would be watching a series of twelve commercials for soft drinks. They were informed that some of the commercials would be repeated because you often see a commercial more than once during a session of television viewing. They were finally instructed to pay close attention to the commercials. The experimenter started the tape and left the room.
The experimental stimuli were presented as part of a series of commercials for eight different soft drinks, with Mountain Dew and Canada Dry being the experimental beverages. The conditioning version of each experimental commercial (the independent variable) consisted of a product segment (CS), followed by an entertaining segment (UCS), and a product consumption segment (filler), all presented in a forward conditioning procedure. The Mountain Dew commercial, for example, consisted of a segment showing ice hitting a bottle of Mountain Dew (CS), followed by a segment showing teenagers jumping into a mountain stream (UCS), with a final filler sequence showing a woman consuming a bottle of Mountain Dew. For the second level of the independent variable non-conditioning versions commercials were presented for the second experimental soda, in this case Canada Dry, and the filler beverages. When Canada Dry was presented as the conditioned beverage, Mountain Dew and the filler beverages represented the non-conditioned commercials.
After viewing the experimental tape, subjects were led into a second room containing a corneal-reflection eye-tracking system. This machine was used to measure the experiments dependent variable, the attention time provided to the conditioned beverages. The dependent measure stimuli consisted of twelve computer-generated video slides, each consisting of a diamond-shaped arrangement of four of the eight beverage brands. Subjects were asked to place his/her chin on the eye-tracking systems chin rest. They were then told that they would be seeing a series of twenty-four slides, with every second slide being a diamond arrangement of soft drink containers. The other slides were fillers that had "X" in the middle, of which the subjects were asked to focus on directly until a stimulus slide appeared. Once subjects understood all instructions the slide presentation began.
When presented in its forward conditioning form (the independent variable), the slides of the Mountain Dew beverage were attended to (the dependent variable) at a significantly higher rate when compared to those beverages previously presented in non-conditioned forms. Similar findings were found when Canada Dry was used as the conditioned beverage. With Canada Dry receiving more and faster attending too when the participants eye movements and patterns were analyzed.
These results suggest that evaluated conditioning techniques can go beyond a simple product-affect transfer. Data shows that conditioning was effective at getting subjects to attend to the forward conditioned products sooner than the non-conditioned ones, an effect that cannot be explained by a simple, single learning system, classical conditioning process. This suggests that a more complex, multiple learning system, must be involved. This system may very well include Pavlovian classical conditioning as a component.
This paper has brought some of the current theories regarding the processes underlying evaluative conditioning into question, helped us reconsider older theories that may in fact still be valid, and has as well brought some new theories into consideration. Two of evaluative conditioning's major theorists Levey and Martin believe that evaluative conditioning is a unique entity, of which many of its components cannot be supported by current Pavlovian human classical conditioning. However, as experiments 1 and 2 showed, the beliefs of Levy, Martin, and many others may have been based on experimental evidence that has evoked strong methodological concerns. When replicated in a highly rigid environmental setting the experiments, which Levey and Martin used as evidence for their theories, actually adds weight towards their opponent's classical conditioning approach. Experiment 3 adds even more support for a classical conditioning explanation of evaluative conditioning's underlying processes, by displaying another classical conditioning component of the evaluative processes, in this case latent inhibition.
With the results of experiments one through three, it would be tempting to conclude that evaluative conditioning is simply classical conditioning in disguise. However, experiment 4 provides evidence that classical conditioning may be no more then just a single component of a much more complex evaluative conditioning system. This experiment provides evidence of a multiple learning process system that is theoretically impossible to explain by classical conditioning alone.
It would appear that the experiments reported in this report have not resolved the nature of evaluative conditioning's processes, but rather has raised even more questions regarding the system. Further research is most definitely needed in order to determine the extent of evaluative conditioning's capabilities, as well as to consider other possible explanations for any learning and conditioning that is observed. Considering the nature and big business of today's advertising and marketing industry it is very likely that the opportunity for such research is readily available, and most likely is already occurring.
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