Speed Modulation in Swimming Frogs

Swimming movements of 7 European green frogs (Rana esculenta) were studied, starting from the detailed analysis of the speed and timing of the propulsive, glide, and recovery phases of their intermittent swimming behavior. First, the authors identified the spatiotemporal factors used by the frogs to modulate their swimming behavior. None of the gait variables correlated strongly with average swimming speed, and no significant correlations were found between variables belonging to different phases. There did not seem to be an obvious control strategy. Instantaneous speeds at the transition of the different phases all increased significantly with average speed, however. The strong correlation between maximal speed at the end of propulsion and the speed averaged over a cycle might reflect the dominance of the propulsive phase in the determination of the overall swimming speed. The modulation of swimming speed thus seemed largely comparable with the regulation of jumping distance. That finding was confirmed in a mathematical model, in which the positive correlations between both glide and recovery speeds, on the one hand, and average speed, on the other, were shown to be only mathematical consequences of the strong impact of the propulsive phase on overall swimming performance. That finding suggests that the correlations did not result from an active control strategy.     

Method matters: effects of explicit versus implicit social comparisons on activation, behavior, and self-views

The authors investigated the impact of explicit versus implicit social comparisons. Simply being primed with a superior or inferior standard (implicit comparison) produced contrast as evidenced by accessibility of self-knowledge (Study 2), intellectual performance (Study 3), and self-ratings (Study 4), inconsistent with the standard. However, when participants were explicitly asked to compare, increased accessibility of a similarity focus (Study 1) and self-knowledge, behavioral performance, and self-ratings congruent with the standard were obtained more easily, indicative of assimilation. Explicit comparisons produced assimilation when the self was seen as mutable (rather than immutable; Study 4), when behavioral consequences were measured immediately after the comparison (rather than later; Study 3), and when the participants described (rather than ranked) their intelligence (Study 5). These findings support the interpretation comparison model. Implications for resolution of empirical inconsistencies in the social comparison literature are discussed.     

The self salience model of other-to-self effects: integrating principles of self-enhancement, complementarity, and imitation

In a series of studies the Self Salience Model of other-to-self effects is tested. This model posits that self-construal salience is an important determinant of whether other-to-self effects follow the principles of self-enhancement, imitation, or complementarity. Participants imagined interactions (Studies 1 and 2) or were confronted (Studies 3 to 5) with dominant, submissive, agreeable, or quarrelsome person targets. Findings support the prediction that subsequent self-evaluations (Studies 1 to 3) and behaviors (Studies 4 and 5) follow the principles of self-enhancement when the personal self is activated (contrast away from undesirable targets, assimilation toward desirable targets); the principles of complementarity when the relational self is activated (contrast on the dominant-submissive dimension, assimilation on the agreeable-quarrelsome dimension); and the principles of imitation when the collective self is activated (assimilation regardless of desirability or dimension).     

The neural correlates of implicit and explicit sequence learning: Interacting networks revealed by the process dissociation procedure

In two H2(15)O PET scan experiments, we investigated the cerebral correlates of explicit and implicit knowledge in a serial reaction time (SRT) task. To do so, we used a novel application of the Process Dissociation Procedure, a behavioral paradigm that makes it possible to separately assess conscious and unconscious contributions to performance during a subsequent sequence generation task. To manipulate the extent to which the repeating sequential pattern was learned explicitly, we varied the pace of the choice reaction time task-a variable that is known to have differential effects on the extent to which sensitivity to sequence structure involves implicit or explicit knowledge. Results showed that activity in the striatum subtends the implicit component of performance during recollection of a learned sequence, whereas the anterior cingulate/mesial prefrontal cortex (ACC/MPFC) supports the explicit component. Most importantly, we found that the ACC/MPFC exerts control on the activity of the striatum during retrieval of the sequence after explicit learning, whereas the activity of these regions is uncoupled when learning had been essentially implicit. These data suggest that implicit learning processes can be successfully controlled by conscious knowledge when learning is essentially explicit. They also supply further evidence for a partial dissociation between the neural substrates supporting conscious and nonconscious components of performance during recollection of a learned sequence.     

Competition, cooperation, and the effects of others on me

Four studies were conducted to test the notion that whether one competes against or cooperates with a comparison target can serve as an important determinant of the direction (contrast or assimilation) of self-evaluative social comparison effects. In Study 1, cooperative-competitive orientation was treated as an individual difference variable, and it was shown that social comparison led to contrast for individuals with a more competitive orientation, whereas assimilation occurred for individuals with a more cooperative orientation. Study 2 replicated this result, treating cooperative-competitive orientation as a contextual variable. In Study 3, it was demonstrated that to obtain this pattern of results it is not necessary for perceivers to believe that they will be either competing or cooperating with the comparison target. Simply activating the relevant concepts is sufficient. The final studies demonstrated that competition activates a "difference" focus and cooperation activates a "similarity" focus.     

The Mirror and I: When private opinions are in conflict with public norms

In two studies it is demonstrated that two self-saliency manipulations, often used interchangeably, can have profoundly different consequences. Whereas self-activation increased stereotyping in highly prejudiced participants, a mirror decreased stereotyping. Results show that this difference can be ascribed to the activation of specific self-aspects. Whereas a mirror increased both private and public self-awareness (and, hence, awareness of the social norm that stereotyping is bad), self-activation increased private self-awareness exclusively (and, hence, awareness of privately held negative stereotypes). The implications of these findings for the relation between self-awareness and conformity to social norms are discussed.     

Terror management and stereotyping: why do people stereotype when mortality is salient?

Three studies examine two routes by which mortality threats may lead to stereotyping. Mortality salience may activate both a comprehension goal and an enhancement goal. Enhancement goals are likely to be more active in situations where intergroup competition or conflict is salient. If this is not the case, then a comprehension goal will predominate. In line with a why-determines-how logic, when mortality salience activates a comprehension goal, both positive and negative stereotyping occur. In contrast, the activation of an enhancement goal only increases negative stereotyping.     

Quantum structure in cognition

The broader scope of our investigations is the search for the way in which concepts and their combinations carry and influence meaning and what this implies for human thought. More specifically, we examine the use of the mathematical formalism of quantum mechanics as a modeling instrument and propose a general mathematical modeling scheme for the combinations of concepts. We point out that quantum mechanical principles, such as superposition and interference, are at the origin of specific effects in cognition related to concept combinations, such as the guppy effect and the overextension and underextension of membership weights of items. We work out a concrete quantum mechanical model for a large set of experimental data of membership weights with overextension and underextension of items with respect to the conjunction and disjunction of pairs of concepts, and show that no classical model is possible for these data. We put forward an explanation by linking the presence of quantum aspects that model concept combinations to the basic process of concept formation. We investigate the implications of our quantum modeling scheme for the structure of human thought, and show the presence of a two-layer structure consisting of a classical logical layer and a quantum conceptual layer. We consider connections between our findings and phenomena such as the disjunction effect and the conjunction fallacy in decision theory, violations of the sure thing principle, and the Allais and Elsberg paradoxes in economics.     

Retracted: Correction or comparison? The effects of prime awareness on social judgments

In previous research on the effects of accessible information on social judgments, divergent explanations have been offered for contrast effects that occur as a consequence of prime awareness. Some authors favor a comparison explanation, whereas others favor a correction explanation. In two studies, we successfully disentangled comparison and correction contrast by demonstrating that whereas correction for unwanted influences is a general process that leads to contrast on various dimensions on which a target is judged, comparison effects are prime specific and occur mainly on comparison relevant dimensions. In addition, our findings indicate that for correction attempts to occur and succeed, respondents must have the feeling that these primes contaminate their target judgments and should be removed from their “true” reaction to the target. When people are not suspicious of the potential contaminating influences of priming stimuli, prime awareness is more likely to lead to prime‐target comparisons than to correction efforts. Copyright © 2009 John Wiley & Sons, Ltd.