Colin Hamilton

The relationship between testosterone and vocal frequencies in human males.

We investigated relationships between circulating levels of salivary testosterone and the fundamental and formant frequencies of male voices in a sample of forty healthy adult males, who recorded their voices and provided saliva samples at 9 am, 12 noon and 3 pm on a single day. The relationship between 2D:4D ratio as a putative biomarker of prenatal testosterone and vocal parameters was also explored. Results supported previous findings for a negative relationship between circulating levels of testosterone and fundamental frequency, with higher testosterone indicating lower fundamental frequency, although the magnitude of the relationship was larger than previously observed. Some limited evidence for a relationship between circulating testosterone and formant dispersion is also found, although this did not reach significance. Diurnal variation in testosterone and fundamental frequency, but not formant dispersion was reported, together with a trend towards an association between the fall in testosterone and the rise in fundamental frequency. Finally, there was no relationship between 2D:4D and the vocal parameters. It is thought that male voices may have deepened over the course of evolution in order to signal dominance and/or to increase the speakers attractiveness. Findings confirm that vocal frequencies may provide an honest signal of the speakers hormonal quality.

The relationship between visuospatial sketchpad capacity and children's mathematical skills

This study examined the association between visuospatial sketchpad (VSSP) capacity and childrens mathematics attainment. The aim of the study was to explore age-related differences in the relationship between the visual and spatial memory subcomponents of the VSSP (Logie, 1995) and a range of mathematical skills. Fifty-one 7- to 8-year-old and fifty-six 9- to 10-year-old primary schoolchildren participated in the study. The Visual Patterns Test and the Block Recall task were employed as VSSP measures. The results revealed a differential pattern of associations between childrens visual and spatial working memory abilities and their mathematical skills. In younger children, the Block Recall task predicted mathematics performance, whereas, in the older children, the Visual Patterns Test was a significant predictor of mathematics performance.

MDMA polydrug users show process-specific central executive impairments coupled with impaired social and emotional judgement processes

In recent years working memory de.cits have been reported in users of MDMA (3,4-methylenedioxymethamphetamine, ecstasy). The current study aimed to assess the impact of MDMA use on three separate central executive processes (set shifting, inhibition and memory updating) and also on ëprefrontalí mediated social and emotional judgement processes. Fifteen polydrug ecstasy users and 15 polydrug non-ecstasy user controls completed a general drug use questionnaire, the Brixton Spatial Anticipation task (set shifting), Backward Digit Span procedure (memory updating), Inhibition of Return (inhibition), an emotional intelligence scale, the Tromso Social Intelligence Scale and the Dysexecutive Questionnaire (DEX). Compared with MDMA-free polydrug controls, MDMA polydrug users showed impairments in set shifting and memory updating, and also in social and emotional judgement processes. The latter two de.cits remained signi.cant after controlling for other drug use. These data lend further support to the proposal that cognitive processes mediated by the prefrontal cortex may be impaired by recreational ecstasy use.

What develops in visuo-spatial working memory development?

The present studies examined the nature of visuo-spatial working memory development using conventional visual span and spatial span measures. Children aged between 6 and 13 years and adults aged 18-38 years were employed as participants. In Study 1, visual span, spatial span, articulation rate, and verbal fluency competencies were measured. In Study 2, visual span and spatial span maintenance was subject to five interference formats: nil, speech articulation, verbal fluency, visual masking, and spatial tapping. Distinct developmental rates were found for the two span tasks, which in the older children were correlated with the verbal fluency measure. Study 2 provided experimental evidence of the contribution of executive and spatial processes to spatial and to visual span maintenance. The results are interpreted as indicating that these memory span procedures make complex demands upon the visuo-spatial working memory architecture and consequently a precise identification of the process that actually develop is compromised. It is suggested that a componential approach where tasks are constructed to tap specific working memory components would afford a more accurate understanding of the development of these processes.

Executive and visuospatial sketchpad resources in euthymic bipolar disorder: Implications for visuospatial working memory architecture

Visuospatial working memory theory is used to interpret the cognitive impairment in euthymic bipolar disorder. Such patients show deficits in the Corsi Blocks Test (CBT) and executive control. To understand these deficits, 20 euthymic bipolar patients and controls were administered the CBT, Visual Patterns Test (VPT), and a new visual memory task designed to make minimal demands on executive resources. Initial analyses validated the visual memory task and implicated executive involvement in the CBT and VPT. Subsequent analyses on a number of tests confirmed CBT and executive deficits while performance was normal on the VPT and visual memory test. ANCOVA indicated that impaired executive function underpinned patients’ CBT performance. Implications for the interface between executive and slave systems of working memory are discussed.

Spatial demonstratives and perceptual space: describing and remembering object location.

Spatial demonstratives - terms including this and that - are among the most common words across all languages. Yet, there are considerable differences between languages in how demonstratives carve up space and the object characteristics they can refer to, challenging the idea that the mapping between spatial demonstratives and the vision and action systems is universal. In seven experiments we show direct parallels between spatial demonstrative usage in English and (non-linguistic) memory for object location, indicating close connections between the language of space and non-linguistic spatial representation. Spatial demonstrative choice in English and immediate memory for object location are affected by a range of parameters - distance, ownership, visibility and familiarity - that are lexicalized in the demonstrative systems of some other languages. The results support a common set of constraints on language used to talk about space and on (non-linguistic) spatial representation itself. Differences in demonstrative systems across languages may emerge from basic distinctions in the representation and memory for object location. In turn, these distinctions offer a building block from which non-spatial uses of demonstratives can develop.

Some evidence of a female advantage in object location memory using ecologically valid stimuli.

A female advantage in object recall is assumed to derive from an adaptation to gathering/foraging. Support for the Gathering Hypothesis has relied upon stimuli and methodologies that lack ecological validity. We report two studies in which object recognition and object location memory were addressed using real plants within naturalistic arrays. In the first, females were significantly quicker than males at finding specific plants in some small arrays, and they made significantly fewer mistakes in a larger array. Next, females also located plants in a large and complex array significantly faster than males. We thus find some support for the Gathering Hypothesis using ecologically valid methods.

Digit Ratio (2D:4D) and Lateralization for Basic Numerical Quantification

Abstract. The ratio between the second and fourth fingers (2D:4D) is supposed to serve as a putative indicator of prenatal testosterone (PT). Significant associations between 2D:4D, childrens basic numerical ability, and the Spatial Numerical Associations of Response Codes (SNARC) effect have recently been reported. The present study explored potential relationships between 2D:4D and the basic numerical ability of subitizing (the rapid enumeration of small quantities) in 80 right-handed adult volunteers. Participants completed a short battery of computerized subitizing and color recognition control tasks with both left and right hands, independently (order counterbalanced). Findings revealed a significant interaction between sex and 2D:4D on reaction time differences for right vs. left hand responses to the subitizing task. While 2D:4D in women showed a significant negative association with a right-hand advantage for the task, a nonsignificant trend in the opposite direction was observed for men. Results...

Visuospatial working memory in children with autism: The effect of a semantic global organization

It has been reported that individuals with Autism Spectrum Disorders (ASD) perceive visual scenes as a sparse set of details rather than as a congruent and meaningful unit, failing in the extraction of the global configuration of the scene. In the present study, children with ASD were compared with typically developing (TD) children, in a visuospatial working memory task, the Visual Patterns Test (VPT). The VPT array was manipulated to vary the semantic affordance of the pattern, high semantic (global) vs. low semantic; temporal parameters were also manipulated within the change detection protocol. Overall, there was no main effect associated with Group, however there was a significant effect associated with Semantics, which was further qualified by an interaction between the Group and Semantic factors; there was only a significant effect of semantics in the TD group. The findings are discussed in light of the weak central coherence theory where the ASD group are unable to make use of long term memory semantics in order to construct global representations of the array.

An event related potential study of inhibitory and attentional control in Williams syndrome adults

The primary aim of the current study was to employ event-related potentials (ERPs) methodology to disentangle the mechanisms related to inhibitory control in older adults with Williams syndrome (WS). Eleven older adults with WS (mean age 42), 16 typically developing adults (mean age 42) and 13 typically developing children (mean age 12) participated in the study. ERPs were recorded during a three-stimulus visual oddball task, during which participants were required to make a response to a rare target stimulus embedded in a train of frequent non-target stimuli. A task-irrelevant infrequent stimulus was also present at randomised intervals during the session. The P3a latency data response related to task-irrelevant stimulus processing was delayed in WS. In addition, the early perceptual N2 amplitude was attenuated. These data are indicative of compromised early monitoring of perceptual input, accompanied by appropriate orientation of responses to task-irrelevant stimuli. However, the P3a delay suggests inefficient evaluation of the task-irrelevant stimuli. These data are discussed in terms of deficits in the disengagement of attentional processes, and the regulation of monitoring processes required for successful inhibition.