Categorical perception of tactile distance

The tactile surface forms a continuous sheet covering the body. And yet, the perceived distance between two touches varies across stimulation sites. Perceived tactile distance is larger when stimuli cross over the wrist, compared to when both fall on either the hand or the forearm. This effect could reflect a categorical distortion of tactile space across body-part boundaries (in which stimuli crossing the wrist boundary are perceptually elongated) or may simply reflect a localised increased in acuity surrounding anatomical landmarks (in which stimuli near the wrist are perceptually elongated). We tested these two interpretations across two experiments, by comparing a well-documented bias to perceive mediolateral tactile distances across the forearm/hand as larger than proximodistal ones along the forearm/hand at three different sites (hand, wrist, and forearm). According to the ‘categorical’ interpretation, tactile distances should be elongated selectively in the proximodistal axis thus reducing the anisotropy. According to the ‘localised acuity’ interpretation, distances will be perceptually elongated in the vicinity of the wrist regardless of orientation, leading to increased overall size without affecting anisotropy. Consistent with the categorical account, we found a reduction in the magnitude of anisotropy at the wrist, with no evidence of a corresponding localised increase in precision. These findings demonstrate that we reference touch to a representation of the body that is categorically segmented into discrete parts, which consequently influences the perception of tactile distance.     

Harm concerns predict moral judgments of suicide: Comment on Rottman,Kelemen and Young (2014)

Two prominent theories offer different perspectives on the role of harm in moral cognition. Dyadic morality suggests that harm-related concerns are pervasive, whereas moral pluralism suggests that these concerns apply only to canonically harmful violations (e.g., murder), and not impure violations (e.g., suicide). Rottman et al. (2014) contrast these two theories by examining moral judgments of suicide. They conclude that suicide wrongness is independent of harm, therefore arguing against dyadic morality and for moral pluralism. However, these conclusions may be overstated; across all these studies, a meta-analysis reveals that harm is a significant predictor of suicide judgments. Moreover, the association between harm and suicide wrongness may be suppressed in individual studies by insufficient power, restrictive exclusion criteria, a single bivariate outlier, and reliance upon the conventional significance threshold of p < .05. In revised analyses harm is robustly associated with suicide wrongness, consistent with dyadic morality.     

The influence of infant-directed speech on 12-month-olds’ intersensory perception of fluent speech

The present study examined whether infant-directed (ID) speech facilitates intersensory matching of audio–visual fluent speech in 12-month-old infants. German-learning infants’ audio–visual matching ability of German and French fluent speech was assessed by using a variant of the intermodal matching procedure, with auditory and visual speech information presented sequentially. In Experiment 1, the sentences were spoken in an adult-directed (AD) manner. Results showed that 12-month-old infants did not exhibit a matching performance for the native, nor for the non-native language. However, Experiment 2 revealed that when ID speech stimuli were used, infants did perceive the relation between auditory and visual speech attributes, but only in response to their native language. Thus, the findings suggest that ID speech might have an influence on the intersensory perception of fluent speech and shed further light on multisensory perceptual narrowing.     

Color‐specific filtering of rival binocular inputs induced by priming1

Abstract: In a situation where the two eyes separately receive two dissimilar images such as a blue square and a red square, the brain is forced to resolve competitive interpretations of the visual inputs. Earlier studies have indicated that adaptation to one of two rival images can control the following competitive perception. Consistent with those studies, the present experiments revealed that immediately after a brief presentation of a color (priming stimulation) to the two eyes, subjects dominantly perceived the other color out of the chromatic rivalry. This effect showed an interocular transfer even if indirect monocular priming was employed, but the filtering out of a primed color did not occur when an unprimed rival image was removed from the other eye. These facts suggest that binocular feature‐detection processes in the human visual system might be responsible for the priming effect on rival images.     

Motion and edge sensitivity in perception of object unity

Although much evidence indicates that young infants perceive unitary objects by analyzing patterns of motion, infants' abilities to perceive object unity by analyzing Gestalt properties and by integrating distinct views of an object over time are in dispute. To address these controversies, four experiments investigated adults' and infants' perception of the unity of a center-occluded, moving rod with misaligned visible edges. Both alignment information and depth information affected adults' and infants' perception of object unity in similar ways, and infants perceived object unity by integrating information about object features over time. However, infants perceived a moving, misaligned, three-dimensional object as indeterminate in its connectedness, whereas adults perceived it as connected behind the occluder. These findings indicate that the effectiveness of common motion in specifying unified surfaces across an occluder is reduced by misalignment of edges. Alignment information enhances perception of object unity either by serving directly as information for unity or by optimizing the detectability of motion-carried information for unity. In addition, young infants are able to retain information about edge orientation over short intervals in determining connectedness via a process of spatiotemporal integration.     

Exploring priming effects of social and non-social attention getters on older infants’ preferences for infant-directed speech

In infant research, various auditory/visual events are often used as attention getters to orient infants to a screen and alert them to upcoming information for their detection, discrimination, and/or recognition. Importantly, the influence of attention-getters on infants’ performance has rarely been systematically evaluated, even though these attention cues could be affecting subsequent information processing. This study investigated whether specific attention-getters could prime infants’ preferences for infant-directed speech (IDS) compared to adult-directed speech (ADS). Both a non-social and a social prime were chosen with the prediction that the social prime would strengthen infants' attention to IDS on a subsequent trial, but the non-social prime would have no differential effect on subsequent attention to either speech type. A total of 20 12- to 18-month old infants were presented with either a nonsocial (rotating form + chimes) or social (smiling female + voice) prime in an infant-controlled, speech preference procedure with both IDS and ADS speech types. Given previous research, we predicted that infants would show significantly more attention on trials during which looking produced IDS, but that this preference would be significantly augmented for infants in the condition receiving a social attention-getter before each trial. Results did not bear out this prediction, although we found a consistent, robust preference for IDS. The results will be discussed in terms of why these attention getters did not affect subsequent processing of two very different speech types, and what future modifications may be necessary in order to examine roles of attention getters in affecting experimental outcomes in infancy research. A secondary benefit of the findings is that we empirically established a growing preference for IDS in infants as old as 18-months of age.