Mismatch negativity and P300 to behaviorally perceptible and imperceptible frequency and intensity contrasts

Mismatch negativity and the P300 have been investigated as electrophysiological indices of behavioral auditory discrimination of duration. Using an oddball paradigm, responses were evoked to stimuli that had been behaviorally demonstrated to be either perceptible or imperceptible. The results indicated P300 events were present with the perceptible contrast but absent for the imperceptible contrast with all participants, while mismatch negativities were present in approximately 80 and 20% of participants to the perceptible and imperceptible contrasts, respectively. The present study extended the findings by applying the same paradigm to the discrimination of spectral and amplitude contrasts. 10 young adults with normal hearing were participants. Assuming that auditory assessment should involve representation and processing in all acoustic domains (i.e., temporal/duration, spectral/frequency, and amplitude/intensity), the effects seen with temporal contrasts were predicted to be similar for spectral and amplitude contrasts. The findings generally illustrated that the P300 was more accurate than the mismatch negativity in reflecting behavioral discrimination. Together, these studies challenge the use of mismatch negativity as an electrophysiological correlate for behavioral discrimination of auditory perceptible contrasts.     

Conditional discrimination in young children: the roles of associative and relational processing

Two experiments examined conditional discrimination in 4- to 6-year-olds. Children learned to choose one of two objects (e.g., circle) when the background was, say, red and to choose the other object (e.g., triangle) when the background was, say, blue. Awareness was assessed and interpreted as a marker of relational processing. In Experiment 1, most 4- and 5-year-olds did not reach the learning criterion. Children in Experiment 2 solved simpler reversal learning problems before the conditional discrimination problems. Most 4- to 6-year-olds reached criterion, but they did not necessarily demonstrate awareness, suggesting that reversal learning and conditional discrimination can be acquired through associative or relational processing. Relational processing increased with age and was used more on simpler problems. Fluid intelligence predicted Problem 2 performance in children who used relational (not associative) processing on Problem 1. Prior experience with simpler problems and awareness of relational structure are influential in children's conditional discrimination.     

Biases in children's and adults' moral judgments

Two experiments examined biases in children's (5/6- and 7/8-year-olds) and adults' moral judgments. Participants at all ages judged that it was worse to produce harm when harm occurred (a) through action rather than inaction (omission bias), (b) when physical contact with the victim was involved (physical contact principle), and (c) when the harm was produced as a direct means to an end rather than as an unintended but foreseeable side effect of the action (intention principle). The youngest participants, however, did not incorporate benefit when making judgments about situations in which harm to one individual resulted in benefit to five individuals. Older participants showed some preference for benefit resulting from action (commission) as opposed to inaction (omission). The findings are discussed in the context of the theory that moral judgments result, in part, from the operation of an inherent, intuitive moral faculty compared with the theory that moral judgments require development of necessary cognitive abilities.     

Comparing measures of attachment: "To whom one turns in times of stress", parental warmth, and partner satisfaction

The Attachment and Clinical Issues Questionnaire (ACIQ; M. A. Lindberg & S. W. Thomas, 2011), was developed over an 18-year period containing 29 scales. The purpose of the present study was to test (a) the validity of the attachment scales in terms of how they predict to whom one turns in times of stress and for affective sharing, and (b) how the attachment scales compared with the Experiences in Close Relationship Questionnaire (ECR) in terms of concurrent, convergent, and discriminant evidence. The relevant secure scales of the ACIQ predicted to whom one turned in study 1, and study 2 demonstrated good convergent evidence with the ECR, but superior concurrent evidence in predicting partner satisfaction, and superior discriminant evidence in differentially correlating with mother and father warmth. Thus, the ACIQ passed essential validity and psychometric tests and was a more robust measure than the ECR with these defining characteristics of attachment.     

The role of the magnocellular visual pathway in the attentional blink

Visual attention has temporal limitations. In the attentional blink (AB) a stream of stimuli such as letters or digits are presented to a participant on a computer monitor at a rapid rate. Embedded in the stream are two targets that the participant must try to identify. Identification of the second target is severely impaired if it is presented within approximately 500ms of the first target. This is the 'blink' in visual attention. In this study we examined the role of the magnocellular visual pathway in the AB. This fast conducting pathway has high temporal resolution and contrast sensitivity. It is also insensitive to the direction of chromatic contrast, and this attribute was exploited in order to isolate its contributions to temporal attention. Colour defined, luminance noise masked AB streams were compared to AB streams of varying achromatic contrast. The four observers, (2F and 2M) aged between 21 and 35years, had normal visual acuity and colour vision. The colour stimuli produced a similar blink to the moderate contrast achromatic stimuli. This indicates that the magnocellular pathway does not have a privileged role in the attentional blink. We provide an explanation of previous apparently contradictory findings in terms of the role of different types of visual masking in the attentional blink.     

An experimental study of behavioural coping strategies in free-ranging female Barbary macaques (Macaca sylvanus)

A fundamental goal of stress research is to understand how individuals cope with challenges. Studies on a range of vertebrate species suggest that three groups of behaviour-affiliative, aggressive and self-directed behaviours-serve as coping strategies. To date, experimental studies of coping behaviour have tended to be conducted in captive conditions; the limited number of studies in free-ranging or wild settings have been observational in nature. We investigated coping behaviours in free-ranging female Barbary macaques (Macaca sylvanus) at Trentham Monkey Forest, UK, using an experimental playback approach to quantify subjects' responses to mildly aversive threat-grunts. Compared to silent control trials, playbacks of threat-grunts increased aggressive behaviours and one of the two self-directed behaviours examined (self-scratching). No such differences were seen for self-grooming, or for any affiliative behaviour. Elevations in the rate of one measure of aggression, lunging, were positively related to an average measure of adrenocortical activity (median faecal glucocorticoid metabolite levels over the study period). Evidence from females in a variety of Old World monkey species, including Barbary macaques, indicates that affiliative behaviours have an important role in coping with stressful events in the medium to longer term. Our results suggest that, in the short term, female Barbary macaques may use aggressive rather than affiliative behaviours in response to mild stress. These findings highlight the importance of considering how coping mechanisms may vary over time after a stressor, and how coping mechanisms relate to adrenocortical activity. Playback approaches like ours provide a powerful, flexible tool to explore issues such as this in free-ranging and wild animal populations.     

Colour inputs to random-dot stereopsis.

Recently it has been claimed by Livingstone and Hubel that, of three anatomically and functionally distinct visual channels (the magnocellular, parvocellular interblob, and blob channels), only the magnocellular channel is involved in the processing of stereoscopic depth. Since the magnocellular system shows little overt colour opponency, the reported loss of the ability to resolve random-dot stereograms defined only by colour contrast seems consistent with this view. However, Julesz observed that reversed-contrast stereograms could be fused if correlated colour information was added. In the present study, 'noise' (non-corresponding) pixels were injected into random-dot stereograms in order to increase fusion time. All six subjects tested were able to achieve stereopsis in less than three minutes when there was only correspondence in colour and not in luminance, and three when luminance contrast was completely reversed. This ability depends on information about the direction of colour contrast, not just the presence of chromatic borders. When luminance and chromatic contrast are defined in terms of signal-to-noise ratios at the photoreceptor mosaic, chromatic information plays at least as important a role in stereopsis as does luminance information, suggesting that the magnocellular channel is not uniquely involved.     

Reasons for the attribution of intent in 7- and 9-year-old children

Seven- and 9-year-old children were presented with drawings which depicted two ambiguous action-outcome sequences and asked to make judgements about the intention of an actor towards another, and then to provide an explanation for the judgement. The design incorporated two levels of actor valence (nice, bad) with two types of outcome quality (good, bad). Judgements were influenced by both valence and outcome factors, but no age effect emerged. Content analysis of the explanations did reveal an age difference in reasoning about social judgements which was associated with the bad outcome. Nine-year-olds used more inference-based explanations which reflected a more objective appraisal of the incident. The explanations of the younger children tended to be dominated by the immediacy of the situation. The findings further highlighted the importance of consistency between actor valence and outcome information relative to the direction of the child's judgement. Inconsistency arising in the context of a bad outcome situation elicited more rigorous explanations from the 9-year-olds.