Production of successive force impulses by the left and right hands

Right-handed participants made ballistic force impulses with the index finger of their left or right hand to match the amplitude of 2 successive visual targets whose onset was separated by 600-850 ms. The targets specified either low- (10% of maximum voluntary contraction; MVC) or high- (25% MVC) force level and were presented in all combinations (low-low, low-high, high-low, high-high). The amplitude of the 1st force impulse affected that of the 2nd, forming an effect that was greatest at the shortest interresponse intervals and that decayed with increasing intervals. This effect was smaller with a shorter time course in the dominant hand than the nondominant hand, suggesting a greater ability of the dominant hand to make successive independent responses.     

The best-worst scaling approach: an alternative to Schwartz's Values Survey

Traditional self-report ratings have some measurement problems that a relatively new method, best-worst scaling (BWS; Finn & Louviere, 1992), may overcome. This alternative method, based on Louviere's BWS, can be used to measure the relative importance or perceived trade-offs among choice alternatives. The method is illustrated as an alternative to the Schwartz Value Survey (SVS; Schwartz, 1992). In a series of samples, it was found that Schwartz values best-worst survey (SVBWS) reproduced Schwartz's (1992) theoretical value structure and supported hypothesized relationships between values and value-expressive behaviors, ethnocentrism, and environmental-related tourism activities. In addition, the SVBWS approach took significantly less respondent time than the traditional SVS approach.     

Inclusion-exclusion of positive and negative past selves: mood congruence as information

The current research challenges the widespread truism that recalling a positive self necessarily increases self-esteem, whereas recalling a negative self necessarily decreases self-esteem. Four experiments demonstrate that chronically happy people show a relative increase in self-esteem by recalling either a positive or a negative self. Chronically sad people, however, show a relative decrease in self-esteem by recalling either a positive or a negative self. These effects are due to divergent perceptions of mood congruence between the recalled self and the current self. Specifically, happy people perceive high mood congruence between a recalled positive self and the current self but low mood congruence between a recalled negative self and the current self. In contrast, sad people perceive high mood congruence between a recalled negative self and the current self but low mood congruence between a recalled positive self and the current self. Independent of chronic mood, mood congruence leads to perceptions of temporal recency, whereas mood incongruence leads to perceptions of temporal distance. In line with the inclusion-exclusion model of social judgment, perceived temporal recency elicits assimilation effects on self-esteem, whereas perceived temporal distance elicits contrast effects on self-esteem.     

Analysis of the role of associative inhibition in perceptual learning by means of the same-different task

In Experiment 1a, participants were exposed, over a series of trials, to separate presentations of 2 similar checkerboard stimuli, AX and BX (where X represents a common background). In one group, AX and BX were presented on alternating trials (intermixed), in another, they were presented in separate blocks of trials (blocked). The intermixed group performed to a higher standard than the blocked group on a same-different test. A superiority of intermixed over blocked exposure was also evident in a within-subject design (Experiment 1b) and when the test required discrimination between a preexposed stimulus and the background (e.g., AX vs. X), even if the background changed between preexposure and test (AY vs. Y) (Experiment 2). In Experiment 3, the intermixed/blocked effect was observed when, in preexposure, stimulus presentations were alternated with the background alone (e.g., AX/X). This suggests that the perceptual learning effect is not the consequence of inhibitory associations between unique features but to increased salience of those features. Experiment 4 confirmed this finding and also ruled out an account of the effect in terms of trial spacing.     

Negational categorization and intergroup behavior

Individuals define themselves, at times, as who they are (e.g., a psychologist) and, at other times, as who they are not (e.g., not an economist). Drawing on social identity, optimal distinctiveness, and balance theories, four studies examined the nature of negational identity relative to affirmational identity. One study explored the conditions that increase negational identification and found that activating the need for distinctiveness increased the accessibility of negational identities. Three additional studies revealed that negational categorization increased outgroup derogation relative to affirmational categorization and the authors argue that this effect is at least partially due to a focus on contrasting the self from the outgroup under negational categorization. Consistent with this argument, outgroup derogation following negational categorization was mitigated when connections to similar others were highlighted. By distinguishing negational identity from affirmational identity, a more complete picture of collective identity and intergroup behavior can start to emerge.     

Should persuasion be affective or cognitive? The moderating effects of need for affect and need for cognition

Three experiments tested the hypothesis that need for affect and need for cognition influence receptivity to affect- and cognition-based persuasive messages. Experiment 1 found that an affective message elicited more positive attitudes among individuals high in need for affect and low in need for cognition, whereas a cognitive message elicited more positive attitudes among individuals low in need for affect and high in need for cognition. Experiment 2 found that individual differences in need for affect influenced receptivity to an affect-based (but not cognition-based) message, whereas individual differences in need for cognition influenced receptivity to a cognition-based (but not affect-based) message. Experiment 3 found that individual differences in need for affect were associated with increased recognition of information from an affect-based (but not cognition-based) message, whereas individual differences in need for cognition were associated with increased recognition of information from a cognition-based (but not affect-based) message. Overall, the studies point to the importance of individual differences in need for affect and need for cognition in understanding how individuals respond to different types of persuasive messages.     

The intermixed-blocked effect in human perceptual learning is not the consequence of trial spacing

A robust finding in humans and animals is that intermixed exposure to 2 similar stimuli (AX/BX) results in better discriminability of those stimuli on test than does exposure to 2 equally similar stimuli in 2 separate blocks (CX_DX)--the intermixed-blocked effect. This intermixed-blocked effect may be an example of the superiority of spaced over massed practice; in the intermixed, but not the blocked exposure regime, each presentation of a given stimulus (e.g., AX) is separated from the next by the presentation of its partner (BX). Two experiments with human participants replicated the intermixed-blocked effect and showed that the effect was not due to the spacing of exposure trials. A mechanism for the intermixed-blocked effect is proposed, which combines theories from associative learning and memory.     

Perceptual deterioration is reflected in the neural response: fMRI study of nappers and non-nappers

Repeated training on a perceptual task can result in performance deterioration. In the case of vision, this practice-dependent decrease, or perceptual deterioration is restored by changing the target orientation, spatial location, or by taking a daytime nap. Behavioral studies suggest the locus of these performance changes to be primary visual cortex. We used fMRI to directly probe whether perceptual deterioration and nap-dependent maintenance of performance can be detected at the level of primary visual cortex. We also asked whether these changes are due to a bottom-up, stimulus-driven response or a top-down plasticity of attentional mechanisms. Subjects were scanned while performing a texture-discrimination task. Half the subjects took a nap between sessions. We measured the relationship between changes in performance and changes in BOLD signal modulation between the two groups. Non-nappers showed performance deterioration that was significantly correlated with decreased BOLD signal modulation, exclusively in area V1 and limited to the bottom-up condition. In contrast, no change was detected in performance and BOLD response in the two conditions for nappers. These results indicate that napping prevented performance deterioration, which was reflected in the fMRI response of neurons in V1. Without a nap, perceptual deterioration was related to decreases in the stimulus-driven, bottom-up representation, rather than decreases in attentional modulation to the stimulus.