The social context of imitation in infancy

Infants increasingly generalize deferred imitation across environmental contexts between 6 and 18 months of age. In three experiments with 126 6-, 9-, 12-, 15-, and 18-month-olds, we examined the role of the social context in deferred imitation. One experimenter demonstrated target actions on a hand puppet, and a second experimenter tested imitation 24h later. When the second experimenter was novel, infants did not exhibit deferred imitation at any age; when infants were preexposed to the second experimenter, all of them did. Imitating immediately after the demonstration also facilitated deferred imitation in a novel social context at all ages but 6 months. Infants' pervasive failure to exhibit deferred imitation in a novel social context may reflect evolutionary selection pressures that favored conservative behavior in social animals.     

Timing variability in circle drawing and tapping: probing the relationship between event and emergent timing

R. Ivry, R. M. Spencer, H. N. Zelaznik, and J. Diedrichsen (2002) have proposed a distinction between timed movements in which a temporal representation is part of the task goal (event timing) and those in which timing properties are emergent. The issue addressed in the present experiment was how timing in conditions conducive to emergent timing becomes established. According to what the authors term the transformation hypothesis, timing initially requires an event-based representation when the temporal goal is defined externally (e.g., by a metronome), but over the first few movement cycles, control processes become established that allow timing to become emergent. Different groups of participants (N = 84) executed either 1 timed interval, 4 timed intervals, or 2 timed intervals separated by a pause. They produced the intervals by either circle drawing, a task associated with emergent timing, or tapping, a task associated with event timing. Analyses of movement variability suggested that similar timing processes were used in the 2 tasks only during the 1st interval. Those results are consistent with the transformation hypothesis and lead to the inference that the transition from event-based control to emergent timing can occur rapidly during continuous movements.     

Nonconscious influence of masked stimuli on response selection is limited to concrete stimulus-response associations

A pattern-masked arrow negatively biased the "free choice" between 2 manual responses or between 2 vocal responses. This apparently nonconscious influence occurred only when the free-choice trials were intermixed randomly with other trials that terminated in fully visible arrows, which directed a response of the same modality (manual vs. vocal) as that involved in the free-choice test trials. This indicates that recent conscious processing of the association between specific stimuli and specific responses is needed to activate the nonconscious influence of masked arrows on response selection. Because this influence occurred only when a concrete association was activated, it appears not to be based on deep comprehension of the stimuli and instead is attributable to simple stimulus-response bonds.     

Perception of visual speed while moving

During self-motion, the world normally appears stationary. In part, this may be due to reductions in visual motion signals during self-motion. In 8 experiments, the authors used magnitude estimation to characterize changes in visual speed perception as a result of biomechanical self-motion alone (treadmill walking), physical translation alone (passive transport), and both biomechanical self-motion and physical translation together (walking). Their results show that each factor alone produces subtractive reductions in visual speed but that subtraction is greatest with both factors together, approximating the sum of the 2 separately. The similarity of results for biomechanical and passive self-motion support H. B. Barlow's (1990) inhibition theory of sensory correlation as a mechanism for implementing H. Wallach's (1987) compensation for self-motion.     

Last but not least

When two three-letter words are flashed up in sequence, observers cannot tell whether the top halves of the words are the same or different. It follows that words, like faces, are processed holistically, not as a set of separate features.     

Perceptions of Dating Violence Following a Sexualor Nonsexual Betrayal of Trust: Effects of Gender, Sexism, Acceptance of Rape Myths, and Vengeance Motivation

College womens (N = 220) and mens (N = 208) perceptions of violence following a betrayal by a romantic partner were studied in an independent groups design that varied gender of the participant, type of betrayal (sexual or nonsexual), and gender of the betrayed individual. Participants read one of four brief vignettes in which the betrayed person slapped his/her partner and made his/her lip bleed. Justification of this action was rated on 10 items. Factor analysis of these items indicated the presence of three factors for men and four for women. Both men and women indicated that hitting the partner, getting even, and being angry were more justifiable following a sexual betrayal. The hitting of a male partner by a betrayed woman was perceived as more justified than the hitting of a female partner by a betrayed man. In absolute terms, hitting and getting even by both women and men were generally viewed as unjustifiable, whereas being angry was viewed as justifiable. For both women and men, scores on the Vengeance Scale (Stuckless & Goranson, 1992) and Rape Myth Acceptance Scale (Lonsway & Fitzgerald, 1995) were related to getting even. For men, the Hostile Sexism Scale (Glick & Fiske, 2001) was related to getting even or being angry and breaking up. Results indicated that perceptions of reactions to betrayal are related to type of betrayal and to the dispositional characteristics of the perceiver.     

Letter-by-letter acquired dyslexia is due to the serial encoding of letters

Letter-by-letter acquired dyslexia (pure alexia) is assumed to be related to the serial encoding of letters, but the evidence for this assumption is somewhat indirect. Here, we demonstrate that the deficit is indeed due to serial encoding by comparing the performance of a letter-by-letter dyslexic reader with the performance of normal readers who were forced to read letter by letter; the data patterns are remarkably similar.     

Two versions of the negative compatibility effect: comment on Lleras and Enns (2004)

A. Lleras and J. T. Enns demonstrated a negative influence of a masked arrow that is attributable to the perceptual interaction between the arrow and the mask when these have properties in common (in this case diagonal lines). Although the present analysis is in agreement that this type of perceptual interaction can occur, it also demonstrates that this is not the only way a masked arrow can produce a negative influence. The most critical finding is that a negative influence occurred even when the arrow and mask did not share the common properties that would be needed for this type of perceptual interaction. This illustrates the version of the negative compatibility effect that was studied by S. T. Klapp and L. B. Hinkley (2002) and others.