Choosing and using tools: capuchins (Cebus apella) use a different metric than tamarins (Saguinus oedipus)

Cotton-top tamarins (Saguinus oedipus) selected canes positioned so that a straight inward pull brought food within reach (M. D. Hauser, 1997; see also record 1997-41347-003). Tamarins failed to retrieve food with canes in other positions, and they did not reposition these canes. In this study, tufted capuchin monkeys (Cebus apella) preferred canes they could pull straight in when these were present, but they also repositioned canes in individually variable ways, and their success at obtaining food with repositioned canes improved with practice. In accord with predictions drawn from ecological psychology, capuchins discovered affordances of canes through exploratory actions with these objects, whereas tamarins did not. Ecological theory predicts these differences on the basis of species-typical manipulative activity, and it provides a useful approach for the study of species differences in tool-using behavior.     

The influence of parafoveal word length and contextual constraint on fixation durations and word skipping in reading

The present study examined the relationship between the predictability of words within a sentence and the availability of parafoveal word length information, on when and where the eyes move in reading. Predictability influenced first-pass reading times when parafoveal word length preview information was correct, but not when it was incorrect. Similarly, for saccades launched from near the target word (wordn), predictability influenced the probability with which it was skipped only when the word length preview was correct. By contrast, for saccades launched farther away from wordn, predictability influenced word skipping regardless of the parafoveal word length preview. Taken together, the data suggest that parafoveal word length preview and predictability can act as a joint constraint on the decision of when and where to move the eyes.     

Enhanced priming for trauma-related material in posttraumatic stress disorder

Intrusive reexperiencing in posttraumatic stress disorder (PTSD) has been linked to perceptual priming for trauma-related material. A prospective longitudinal study (N = 69) investigated perceptual priming for trauma-related, general threat, and neutral words in assault survivors with and without PTSD, using a new version of the word-stem completion task. Survivors with PTSD showed enhanced priming for trauma-related words. Furthermore, priming for trauma-related words measured soon after the trauma was associated with subsequent PTSD severity at 3, 6, and 9 months. The enhanced priming effect was specific to trauma-related words. Enhanced perceptual priming for traumatic material appears to be one of the cognitive processes operating in PTSD.     

The relationship of body image dissatisfaction to cigarette smoking in college students

This study examined the association of cigarette smoking status and body image dissatisfaction as measured by the Multidimensional Body-Self Relations Questionnaire (MBSRQ), in 1575 young adult college students, 18–24 years of age. Respondents were current cigarette smokers (N = 482) or never tobacco users (N = 1093). Smoking status was found to be significantly associated with 5 of the 10 MBSRQ subscales, with current smokers having lower scores on Fitness Orientation, Health Evaluation and Health Orientation (all p < 0.001) and higher scores on Appearance Orientation (p = 0.01) and Overweight Preoccupation (p = 0.03) compared with never tobacco users. Furthermore, among current smokers, a higher number of days smoked in the last 30 days were associated with lower scores on all MBSRQ subscales, except Self-Classified Weight. In terms of clinical implications, interventions for smoking cessation among college students might benefit from inclusion of components for addressing body image dissatisfaction and improving health beliefs.     

The associative memory deficit of older adults: further support using face-name associations

Previous studies have established an associative deficit hypothesis (Naveh-Benjamin, 2000), which attributes part of older adults' deficient episodic memory performance to their difficulty in creating cohesive episodes. In this article, the authors further evaluate this hypothesis, using ecologically relevant materials. Young and old participants studied name-face pairs and were then tested on their recognition memory for the names, faces, and the name-face pairs. The results extend the conditions under which older adults exhibit an associative deficit. They also show that reduced attentional resources are not the sole mediator of this deficit.     

Stabilization and destabilization of perception--action patterns influence the self-organized recruitment of degrees of freedom

The recruitment of an additional biomechanical degree of freedom in a unimanual rhythmic task was explored. Subjects were asked to synchronize adduction or abduction of their right index finger with a metronome, the frequency of which was increased systematically. In addition, haptic contact on or off the metronome beat was provided. Results showed that the pattern exhibiting the highest intrinsic stability recruited the vertical plane more than did the less stable one. Moreover, presence and location of haptic contact modulated coordination stability and therefore induced changes in the recruitment of the vertical plane. Thus, a trade-off was shown between coordination stability on the horizontal plane and recruitment of the vertical one. These findings suggest that recruitment of degrees of freedom is governed by general principles of coordination dynamics.     

Distant melodies: statistical learning of nonadjacent dependencies in tone sequences

Human listeners can keep track of statistical regularities among temporally adjacent elements in both speech and musical streams. However, for speech streams, when statistical regularities occur among nonadjacent elements, only certain types of patterns are acquired. Here, using musical tone sequences, the authors investigate nonadjacent learning. When the elements were all similar in pitch range and timbre, learners acquired moderate regularities among adjacent tones but did not acquire highly consistent regularities among nonadjacent tones. However, when elements differed in pitch range or timbre, learners acquired statistical regularities among the similar, but temporally nonadjacent, elements. Finally, with a moderate grouping cue, both adjacent and nonadjacent statistics were learned, indicating that statistical learning is governed not only by temporal adjacency but also by Gestalt principles of similarity.     

Six-year-olds' difficulties handling intensional contexts

Previous research shows that children have difficulties handling intensional contexts even when they can pass a test of false belief (e.g. Cognition 67 (1998) 287; Cognition 25 (1987) 289). Some authors (Perner, J. (1991). Understanding the representational mind. Cambridge, MA: MIT Press; Cognition 25 (1987) 289) place these difficulties in the linguistic and not the mental representational domain. The experiments reported here examined whether 6-year-old children could answer questions in an intensional context that did not require the explicit verbal characterization of a belief. We replicated previous findings and found that children answered according to their own knowledge in an intensional context. This occurred even though they responded by choosing a picture to insert into a protagonist's thought bubble rather than report the belief verbally. Children could correctly answer questions about the knowledge state of the protagonist and pass a test of false belief. Further experiments ruled out methodological explanations. Experiment 2 showed that the difference in answering according to own knowledge between the false belief and intensional stories is not accounted for by procedural factors in the two types of test. Experiment 3 revealed that children did not answer according to their own knowledge by default. Experiment 4 suggested that answering according to own knowledge was not a result of pictorial salience. Results are discussed in relation to the simulation-theory debate.     

Tooth color: effects on judgments of attractiveness and age

Tooth whitening has become a very popular procedure. Advertisements for whitening products imply that whiter teeth are more attractive than yellower teeth. We tested this idea empirically by manipulating the tooth color of pictures of male and female targets. Participants' ratings of attractiveness were not influenced by tooth color. Exp. 2 yielded a negative correlation between attractiveness and age ratings: targets judged to be older were rated as less attractive. Unless whiter teeth help in some other way, e.g., improved self-esteem or confidence, it seems that tooth whitening procedures or products are not associated with increased attractiveness to others.