Caffeine, Cognition, and Persuasion: Evidence for Caffeine Increasing the Systematic Processing of Persuasive Messages

Caffeine is known to increase arousal, attention, and information processing–all factors implicated in facilitating persuasion. In a standard attitude-change paradigm, participants consumed an orange-juice drink that either contained caffeine (3.5 mg/kg body weight) or did not (placebo) prior to reading a counterattitudinal communication (anti-voluntary euthanasia). Participants then completed a thought-listing task and a number of attitude scales. The first experiment showed that those who consumed caffeine showed greater agreement with the communication (direct attitude: voluntary euthanasia) and on an issue related to, but not contained in, the communication (indirect attitude: abortion). The order in which direct and indirect attitudes were measured did not affect the results. A second experiment manipulated the quality of the arguments in the message (strong vs. weak) to determine whether systematic processing had occurred. There was evidence that systematic processing occurred in both drink conditions, but was greater for those who had consumed caffeine. In both experiments, the amount of message-congruent thinking mediated persuasion. These results show that caffeine can increase the extent to which people systematically process and arc influenced by a persuasive communication.     

Effects of caffeine on persuasion and attitude change: The role of secondary tasks in manipulating systematic message processing

Two experiments are reported that examine the effects of caffeine consumption on attitude change by using different secondary tasks to manipulate message processing. The first experiment employed an orientating task whilst the second experiment employed a distracter task. In both experiments participants consumed an orange‐juice drink that either contained caffeine (3.5 mg/kg body weight) or did not contain caffeine (placebo) prior to reading a counter‐attitudinal communication. The results across both experiments were similar. When message processing was reduced or under high distraction, there was no attitude change irrespective of caffeine consumption. However, when message processing was enhanced or under low distraction, there was greater attitude change in the caffeine vs. placebo conditions. Furthermore, attitudes formed after caffeine consumption resisted counter‐persuasion (Experiment 1) and led to indirect attitude change (Experiment 2). The extent that participants engaged in message‐congruent thinking mediated the amount of attitude change. These results provide evidence that moderate amounts of caffeine increase systematic processing of the arguments in the message resulting in greater agreement. Copyright © 2006 John Wiley & Sons, Ltd.     

Systematic and heuristic processing of majority and minority-endorsed messages: the effects of varying outcome relevance and levels of orientation on attitude and message processing

Two experiments investigated the conditions under which majority and minority sources instigate systematic processing of their messages. Both experiments crossed source status (majority vs. minority) with message quality (strong vs. weak arguments). In each experiment, message elaboration was manipulated by varying either motivational (outcome relevance, Experiment 1) or cognitive (orientating tasks, Experiment 2) factors. The results showed that when either motivational or cognitive factors encouraged low message elaboration, there was heuristic acceptance of the majority position without detailed message processing. When the level of message elaboration was intermediate, there was message processing only for the minority source. Finally, when message elaboration was high, there was message processing for both source conditions. These results show that majority and minority influence is sensitive to motivational and cognitive factors that constrain or enhance message elaboration and that both sources can lead to systematic processing under specific circumstances.     

Levels of consensus and majority and minority influence

Three experiments are reported which examine the effects of consensus information on majority and minority influence. In all experiments two levels of consensus difference were examined; large (82% versus 18%) and small (52% versus 48%). Experiment 1 showed that a majority source had more influence than a minority source, irrespective of consensus level. Experiment 2 examined the cause of this effect by presenting only the source label (‘majority’ versus ‘minority’), only the consensus information (percentages) or both. The superior influence of the majority was again found when either (a) both source label and consensus information were given (replicating Experiment 1) and (b) only consensus information was given, but not when (c) only the source label was given. The results showed majority influence was due to the consensus information indicating more than 50% of the population supported that position. Experiment 3 also manipulated message quality (strong versus weak arguments) to identify whether systematic processing had occurred. Message quality only had an impact with the minority of 18%. These studies show that consensus information has different effects for majority and minority influence. For majority influence, having over 50% support is sufficient to cause compliance while for a minority there are advantages to being numerically small, in terms of leading to detailed processing of its message. Copyright © 2002 John Wiley & Sons, Ltd.     

Minority influence: the role of ambivalence toward the source

According to literature on social influence, a minority source may indirectly influence group members by fostering ambivalent reactions. Two studies were carried out in order to provide empirical support for this theoretical assumption. In Study 1 participants (n = 133), were exposed to a counter‐attitudinal minority message and ambivalence was manipulated by facilitating the accessibility of either ambivalent (positive and negative) or univalent (positive or negative) thoughts toward the source. We predicted and found more indirect influence in ambivalent condition than in univalent conditions. No effect of ambivalence on direct influence was found. In Study 2 (n = 127), ambivalence was measured and two possible antecedents of ambivalence, consistency of the minority and personal relevance of the topic for participants, were taken into account. Findings suggest that ambivalence mediates the effects of the two factors on indirect influence. In sum, these studies provide evidence of the importance of ambivalence in minority influence context, an early assumption that was still lacking in strong empirical support. Copyright © 2007 John Wiley & Sons, Ltd.     

Paradoxical effects of categorization in minority influence: When being an outgroup is an advantage

In a 2 × 2 factorial design, 165 high school girls gave their opinions about abortion (direct influence) and about contraception (indirect ifluence) after reading a message advocating abortion said to have been written by either an ingroup (same sex) or an outgroup (opposite sex) minority and explicitly opposed by the majority opinion of either the ingroup or the outgroup. Results show that there is less direct influence when the ingroup majority is opposed to the minority, and more direct influence when the process of identification is less involved. Indirect influence appears in an intergroup context where categorization of majority and minority into different groups is superimposed on their ideological dissent, which has the effect of allowing recognition of the minority's distinctiveness and validity over and above the discrimination that appears at the direct influence level. In discussing the results, a theoretical integration of social comparison and validation processes is proposed as a step towards explaining the diversity of minority influence phenomena.     

Majority versus minority influence: when,not whether,source status instigates heuristic or systematic processing

Two experiments investigated the extent of message processing of a persuasive communication proposed by either a numerical majority or minority. Both experiments crossed source status (majority versus minority) with message quality (strong versus weak arguments) to determine which source condition is associated with systematic processing. The first experiment showed a reliable difference between strong and weak messages, indicating systematic processing had occurred, for a minority irrespective of message direction (pro‐ versus counter‐attitudinal), but not for a majority. The second experiment showed that message outcome moderates when a majority or a minority leads to systematic processing. When the message argued for a negative personal outcome, there was systematic processing only for the majority source; but when the message did not argue for a negative personal outcome, there was systematic processing only for the minority source. Thus one key moderator of whether a majority or minority source leads to message processing is whether the topic induces defensive processing motivated by self‐interest. Copyright © 2002 John Wiley & Sons, Ltd.     

Indirect majority and minority influence: An exploratory study

In a 2 × 2 design, 85 subjects were asked to estimate the size of angles (direct influence) that were either 90 or 85°, after being confronted with incorrect judgements of a majority (88 per cent) or a minority (12 per cent) of people estimating the angles at 50°. Additionally, pre- and post-test measures were used to establish indirect influence on subjects' judgements pertaining to acute angles (i.e. on the estimation of the length of lines constituting the angles, and on the imaginary weight of figures represented by these angles). Overall, little direct influence is observed. This may partly be due to the introduction of a denial of the credibility of the source in all conditions. In fact, some evidence of direct influence is only found in the majority–85° angles condition. An instance of indirect influence (on the estimation of length of lines) appeared as the result of a majority stance when the angles in the experimental phase were 90°. When these angles were 85°, indirect minority influence (on the estimation of weight of figures) was observed. These effects had been predicted on the basis of the hypothesis stating that indirect majority influence would be possible when subjects expected consensus on the correct response (in the 90° angles condition), without being able to reach consensus at the manifest level (because of the denial and the restriction imposed by the clear shape of 90° angles). Indirect minority influence was hypothesized to be stronger in a situation that allows for diverse responses (i.e. for 85° angles).     

Majority versus minority influence and prediction of behavioral intentions and behavior

Two experiments examined the effects of majority and minority influence on attitude-consistent behavioral intentions. In the first experiment, when attitudes were changed via minority influence there was a greater likelihood to engage in an attitude-consistent behavioral intention than when attitudes were changed via majority influence. This suggests that minority influence leads to stronger attitudes (based on systematic processing) that are more predictive of behavioral intentions, while attitude change via majority influence is due to compliance through non-systematic processing. Further support for this interpretation comes from the finding that the amount of message-congruent elaboration mediated behavioral intention. When there was no attitude change, there was no impact on behavioral intention to engage in an attitude-consistent behavior. Experiment 2 explored the role of personal relevance of the topic and also included a real behavioral measure. When the topic was of low personal relevance, the same pattern was found as Experiment 1. When the topic was of high personal relevance, thus increasing the motivation to engage in systematic processing, attitudes changed by both a majority and minority source increased behavioral intention and actual behavior. The results are consistent with the view that both majorities and minorities can lead to different processes and consequences under different situations.     

Divergence vs. ambivalence: effects of personal relevance on minority influence

According to the literature on social influence, a minority source can induce two main cognitive processes: validation and divergence. The aim of the present study was to determine if the two processes are jointly or alternatively activated. We hypothesized that the process stimulated by the minority source would be different according to the personal relevance of the issue for the participants. Specifically, we predicted that a minority would induce more validation (i.e. ambivalent thoughts about the issue) in the low relevance condition rather than in the high relevance condition. On the other hand, the minority would produce more divergence (i.e. alternative proposals) in the high relevance condition rather than in the low relevance condition. Two experiments in which the participants were exposed to a counter‐attitudinal message of a minority or a majority supported these predictions. Moreover, in Study 1 evidence has also been found that a minority source fosters more pertinent (but not more original) proposals in the high relevance condition rather than in the low relevance condition, whereas in Study 2 ambivalence (other than divergence) appeared to be correlated with, but not a significant mediator of, indirect influence. The implications of these findings for minority influence theory are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Majority versus minority influence: the role of message processing in determining resistance to counter‐persuasion

Two experiments examined the extent to which attitudes changed following majority and minority influence are resistant to counter‐persuasion. In both experiments participants' attitudes were measured after being exposed to two messages, delayed in time, which argued opposite positions (initial message and counter‐message). In the first experiment, attitudes following minority endorsement of the initial message were more resistant to a second counter‐message only when the initial message contained strong versus weak arguments. Attitudes changed following majority influence did not resist the second counter‐message and returned to their pre‐test level. Experiment 2 varied whether memory was warned (i.e., message recipients expected to recall the message) or not, to manipulate message processing. When memory was warned, which should increase message processing, attitudes changed following both majority and minority influence resisted the second counter‐message. The results support the view that minority influence instigates systematic processing of its arguments, leading to attitudes that resist counter‐persuasion. Attitudes formed following majority influence yield to counter‐persuasion unless there is a secondary task that encourages message processing. Copyright © 2007 John Wiley & Sons, Ltd.     

Compliance,conversion and the Asch paradigm

120 subjects took part in an Asch type experiment, using a material which was suitable for the measurement of indirect influence. The subjects were given the consistent incorrect response of a source which was either a majority (the response given by 88 per cent of a parent population of college students) or a minority (12 per cent). Part of the subjects were told that the experiment was investigating perceptual illusions and an example of such illusions was given. An authority condition was also introduced: the experimenter himself gave the incorrect response. A control condition did not involve any influence or illusion. The results show that direct influence increases when there is a stronger symbolic social pressure. They also show that an indirect influence may be induced by a numerical majority (provided that the subjects believe that there is an illusion) as well as a numerical minority (provided that an illusion does not invalidate its response). These results underline how important it is to control the exact significance of experimental situations that are supposed to represent the psychological conditions of majority or minority influence.     

Group conversion versus group expansion as modes of change in majority and minority positions: all losses hurt but only some gains gratify

This study examined reactions to minority and majority positions that were either stable or reversed through group conversion that transformed opponents (supporters) of the minority (majority) into supporters (opponents) or through group expansion that brought new supporters (opponents) for the minority (majority) into the group. Minorities who became majorities through group expansion, compared with those who changed through group conversion, perceived their supporters and the overall group as significantly more similar to the self, and had significantly higher expectations for future positive interactions within the group. Perception of similarity with the supporters mediated the effect of the experimental conditions on perception of the overall group-self similarity. Implications of changes through conversion and expansion for the functioning of social groups are discussed.     

Minority influence: The effects of social status of an inclusive versus exclusive group

An experiment investigated the effects of source status (high versus low) and source's attitude towards the target (Inclusive versus éxclusive) on minority influence. It was predicted that an inclusive minority in the high-status source condition would primarily have a direct impact (compliance), while in the low-status source condition it would have little direct or indirect influence but would stimulate autonomous cognitive work (divergence) Moreover, exclusive minorities, irrespective of status, would have a mainly indirect impact (conversion) Results appear to confirm the hypotheses with two significant qualifications: First, minority status interacts with subjects' initial attitude, furthering or hindering indirect influence; second, an exclusive minority encourages the production of externally-generated thoughts, albeit only in low-status source condition. The study also provided some information on the relationship between indirect influence and divergence, and between the quantity and the quality of cognitive production.     

Resistance to persuasive messages as a function of majority and minority source status

Three experiments examined the extent to which attitudes following majority and minority influence are resistant to counter-persuasion. In Experiment 1, participants’ attitudes were measured after being exposed to two messages which argued opposite positions (initial pro-attitudinal message and subsequent, counter-attitudinal counter-message). Attitudes following minority endorsement of the initial message were more resistant to a (second) counter-message than attitudes following majority endorsement of the initial message. Experiment 2 replicated this finding when the message direction was reversed (counter-attitudinal initial message and pro-attitudinal counter-message) and showed that the level of message elaboration mediated the amount of attitude resistance. Experiment 3 included conditions where participants received only the counter-message and showed that minority-source participants had resisted the second message (counter-message) rather than being influenced by it. These results show that minority influence induces systematic processing of its arguments which leads to attitudes which are resistant to counter-persuasion.     

Studies on latent influence by the spectrometer method I: The impact of psychologization in the case of conversion by a minority or a majority

The effects of psychologization on the conversion phenomenon were studied for cases where influence was exerted either by a minority or by a majority. In a 2×2×3 ANOVA design (minority source versus majority source, personality versus aesthetics, phases) 48 subjects are faced with a confederate who represents either 18.2 per cent or 81.8 per cent of a population and consistently responds green when an objectively blue slide is shown. Colour perception is said to be associated with either aesthetic or personality factors. The prediction is in this last case that psychologization of the majority induces conversion of the subjects, while psychologization of the minority stands in the way of this latent influence. Influence is measured by four response levels for each trial of the three phases (pre-influence, post-influence in the presence or in the absence of the influence source). Manifest influence is measured in terms of the Subjects' Judgements and by the way in which they adjust their stimulus colour perception, as determined with the help of a spectrometer. The latent influence is reflected by the subjects' judgements about the colour of the afterimage upon presentation of the stimulus, as measured on a nine-point scale and with the help of spectral adjustments of this afterimage. The subjects having been influenced without being aware of their conversion shows up in the shifts toward green or the complementary colour of green. Results indicate a cross-over for the effect of indirect influence. Under the personality condition, psychologization has the anticipated effect. The majority is the only one to produce a conversion. The attenuating effect of minority influence again manrfests itserf (Mugny and Papastamou, 1980). Under the aesthetic condition, non-psychologization also induces latent and perceptive shifts, but they go in the opposite direction and coincide closely with other results (Moscovici and Personnaz, 1980; Personnaz, 1981). In this condition, only the minority exerts an influence on all three levels.     

Minority influence and musical preference: Innovation by conversion not coercion

Studied the effect of social categorization, strength of influence and predisposition to influence on social influence concerning musical preferences. One-hundred and sixty-eight French adolescents (age 15 years) were assigned to the eight conditions of a 2 (social categorization: majority/minority) × 2 (strength of influence: strong/weak) × 2 (predisposition to influence: pervious/impervious) design. Influence source was an opinion poll based on pupils from two types of secondary school. Direct influence was exerted from ‘hard-rock’ to ‘new wave’ music; indirect influence was measured by subjects' preferences for hard-rock versus ‘contemporary’ music. Ratings of the source were also elicited. Analyses of variance revealed indirect influence to be significantly greater with the minority than the majority source (p < 0.02). Indirect influence was especially high for subjects with a clear predisposition to influence and when the influence was weak (p < 0.0005). Further analyses confirmed the effect to be due to the actual numbers of subjects influenced. The study thus demonstrated the generalizability of the ‘conversion’ notion (minority influence on an indirect level) from numerical to social minorities.     

Conversion theory and simultaneous majority/minority influence: Can reactance offer an alternative explanation?

This study tested whether reactance theory can account for private acceptance of a minority opinion under simultaneous majority/minority influence (reactance against majority rather than conversion toward minority). Subjects were either exposed to simultaneous majority /minority influence or to a majority source only. As predicted by conversion theory, subjects moved away from the majority only in private and in the presence of a consistent minority. In the absence of a consistent minority, subjects accepted the majority opinion in private, ruling out reactance as an alternative explanation.     

想象接触对大学生内隐态度和外显态度的影响

本研究旨在探讨想象接触对不同民族群体内隐态度和外显态度的影响。实验1和实验2分别随机选取不同先前接触经验的汉族大学生和维吾尔族大学生进行想象接触,采用“单类内隐联想测验(SC-IAT)”和外显态度量表评估不同条件下的内隐态度和外显态度。结果表明：想象接触显著提高了不同群体对外群体的内隐态度,对外显态度影响不显著;而先前接触经验对不同群体的内隐态度影响不显著,对外显态度影响显著。研究还发现,即使是已经发生过面对面接触的个体,也可以通过想象接触来提高对外群体的内隐态度,进一步拓展了想象接触在整个群际接触体系中地位和作用。