Fran Allard

Attentional biases and the right-ear effect in dichotic listening ☆

Most dichotic listening experiments permit subjects to deploy attention in any way they choose. We argue that this adds uncontrolled variance to the observed right-ear advantage. In the first experiment, more robust laterality effects were obtained in an identification task with focused than with divided attention. Such differences were not found in the second experiment, when a detection procedure was used. Virtually all the laterality effect observed in the second study could be attributed to subjects who were biased attenders, in the sense that they exhibited more intrusions from the right ear to the left than vice versa. However, rather than indicating that laterality effects are simply attentional bias, this effect can be attributed to an asymmetry of perceptual discrimination.

Visual hemifield differences depend on typeface.

Abstract In a tachistoscopic recognition experiment, visual field differences were shown to depend on typeface. The majority of typefaces exhibited a right visual field superiority, but several showed a left field superiority. Further experimentation revealed that the left visual field superiorities were reliable. Laterality effects were most closely related to the dimension of printlike-to-scriptlike, with left visual field effects being obtained with scriptlike material. These results indicate that visual field differences cannot be explained in terms of verbal response requirements. Instead, they suggest that initial preprocessing is carried out more efficiently by the right hemisphere, and that this preprocessing is more important for certain types of lettering than for others.

Influence of a visuo-spatial, verbal and central executive working memory task on postural control.

In this study, participants were required to perform different working memory (WM) tasks (a verbal task, a visuo-spatial task with two levels of difficulty and a central executive task) under different challenges to postural control (sitting, shoulder width stance and tandem stance). When a WM task was added, changes in postural sway were characterized by an increase in frequency and decrease in amplitude of sway indicating a tighter control. We found no changes in postural control between the different types of WM tasks, which might support a general capacity limitation hypothesis. However, no changes were found in performance of the WM when postural stance was modified and no changes were found in postural sway, when the difficulty level of the visuo-spatial task was modified. Consequently, the results seem to indicate that the addition of a WM task, regardless of task type or task difficulty, forces the central nervous system to choose a tighter control strategy.

What guides the selection of alternate foot placement during locomotion in humans

Abstract Our goal was to understand the bases for selection of alternate foot placement during locomotion when the normal landing area is undesirable. In this study, a light spot of different shapes and sizes simulated an undesirable landing area. Participants were required to avoid stepping on this spot under different time constraints. Alternate chosen foot placements were categorised into one of eight choices. Results showed that selection of alternate foot placement is systematic. There is a single dominant choice for each combination of light spot and normal landing spot. The dominant choice minimises the displacement of the foot from its normal landing spot (less than half a foot length). If several response choices satisfy this criterion, three selection strategies are used to guide foot placement: placing the foot in the plane of progression, choosing to take a longer step over a shorter step and selecting a medial rather than lateral foot placement. All these alternate foot-placement choices require minimal changes to the ongoing locomotor muscle activity, pose minimal threat to dynamic stability, allow for quick initiation of change in ongoing movement and ensure that the locomotor task runs without interruption. Thus, alternate foot-placement choices are dependent not only on visual input about the location, size and shape of the undesirable surface, but also on the relationship between the characteristics of the undesirable surface and the normal landing area.

Memory of a speaker's voice: Reaction time to same- or different-voiced letters

Subjects were presented with a sequence of two letters, each letter spoken in either a male or female voice. On each trial, the subject was required to indicate, as quickly as possible, whether the two letters had the same name. Reaction times (RTs) were faster for letters spoken in the same voice for both “same” and “different” responses, even when letters were separated by 8 s. These results are incompatible with the notion of physical and name codes in auditory memory since a “different” response should always be based on a comparison of letter names and should not be influenced by voice quality. It was also found that RTs were not influenced by the phonemic distinctive feature similarity of the letters.

Burst Cues, Transition Cues, and Hemispheric Specialization with Real Speech Sounds:

Subjects listening to dichotically presented real speech stop and fricative consonants, with and without transitions, showed larger laterality effects in the transition-less condition. In a second study, laterality effects for burst cues and transition cues were compared; using the stop consonants /b/ and /d/. Again, burst cues produced a larger laterality effect. These results are not compatible with a lateralized speech “decoder”, and are interpreted as favoring a Semmes (1968) model of hemispheric differences, differential processing.

Skilled memory in expert figure skaters

The present studies extend skilled-memory theory to a domain involving the performance of motor sequences. Skilled figure skaters were better able than their less skilled counterparts to perform short skating sequences that were choreographed, rather than randomly constructed. Expert skaters encoded sequences for performance very differently from the way in which they encoded sequences that were verbally presented for verbal recall. Tasks interpolated between sequence and recall showed no significant influence on recall accuracy, implicating long-term memory in skating memory. There was little evidence for the use of retrieval structures when skaters learned the brief sequences used throughout these studies. Finally, expert skaters were able to judge the similarity of two skating elements faster than less skilled skaters, indicating a faster access to semantic memory for experts. The data indicate that skaters show many of the same skilled-memory characteristics as have been described in other skill domains involving memorization, such as digit span and memory for dinner orders. Correspondence should be addressed to Janice M. Deakin,

Do auditory perceptual asymmetries develop

Two studies investigated dichotic listening performance in school-age children. The first employed lists of numbers, single pairs of nonsense syllables, and single pairs of words. None of these materials produce any age-related effects, although a strong right-ear effect was observed with all. When subjects were permitted free recall of number lists, they tended to initiate report with items from the right ear, indicating an attentional bias towards the right. When this was corrected statistically, most of the laterality effect disappeared, suggesting that attentional biases make a major contribution to observed laterality effects. The second study involved word pairs, environmental sounds, and a word pair condition in which the deployment of attention was controlled by instruction. The two verbal tasks again showed a large right-ear effect, but no laterality effects were found for environmental sounds. The monitoring experiment corroborated the earlier finding that children tend to bias their attention to the right, but this attentional bias could not account for the whole laterality effect. It is concluded that a right-ear perceptual advantage exists for verbal material in children, and that there is no evidence for any change in this laterality effect with age.

Chapter 6 Declarative Knowledge in Skilled Motor Performance: Byproduct or Constituent?

Publisher Summary This chapter discusses three studies in the domains of hockey, figure skating and diving, and basketball, to determine the relationship between what a person does and what a person knows. It is possible that declarative knowledge is the consequence of the number of hours spent by expert motor performers in their particular environment, and is not essential for the expression of the actual skill. The three lines of evidence are presented, from studies of the classification of pictures, of the advantage in judging a sport enjoyed by those who can also perform the skills required of the activity, and of the different types of declarative knowledge required by experts having different roles within a particular skill domain, all speak to the importance of declarative knowledge in expert motor performance. Declarative knowledge is a constituent of skill, rather than a byproduct of time spent in a particular domain. Therefore, it is important to determine the nature of the procedural-declarative relationship; to examine how it is possible for knowing and doing to influence each other and how the two forms of knowledge impact learning.

Aging does not affect generalized postural motor learning in response to variable amplitude oscillations of the support surface.

Postural motor learning for dynamic balance tasks has been demonstrated in healthy older adults (Van Ooteghem et al. in Exp Brain Res 199(2):185–193, 2009). The purpose of this study was to investigate the type of knowledge (general or specific) obtained with balance training in this age group and to examine whether embedding perturbation regularities within a balance task masks specific learning. Two groups of older adults maintained balance on a translating platform that oscillated with variable amplitude and constant frequency. One group was trained using an embedded-sequence (ES) protocol which contained the same 15-s sequence of variable amplitude oscillations in the middle of each trial. A second group was trained using a looped-sequence (LS) protocol which contained a 15-s sequence repeated three times to form each trial. All trials were 45 s. Participants were not informed of any repetition. To examine learning, participants performed a retention test following a 24-h delay. LS participants also completed a transfer task. Specificity of learning was examined by comparing performance for repeated versus random sequences (ES) and training versus transfer sequences (LS). Performance was measured by deriving spatial and temporal measures of whole body center of mass (COM) and trunk orientation. Both groups improved performance with practice as characterized by reduced COM displacement, improved COM–platform phase relationships, and decreased angular trunk motion. Furthermore, improvements reflected general rather than specific postural motor learning regardless of training protocol (ES or LS). This finding is similar to young adults (Van Ooteghem et al. in Exp Brain Res 187(4):603–611, 2008) and indicates that age does not influence the type of learning which occurs for balance control.