Adaptation to continuous perturbation of balance: progressive reduction of postural muscle activity with invariant or increasing oscillations of the center of mass depending on perturbation frequency and vision conditions

We investigated the adaptation of balancing behavior during a continuous, predictable perturbation of stance consisting of 3-min backward and forward horizontal sinusoidal oscillations of the support base. Two visual conditions (eyes-open, EO; eyes-closed, EC) and two oscillation frequencies (LF, 0.2 Hz; HF, 0.6 Hz) were used. Center of Mass (CoM) and Center of Pressure (CoP) oscillations and EMG of Soleus (Sol) and Tibialis Anterior (TA) were recorded. The time course of each variable was estimated through an exponential model. An adaptation index allowed comparison of the degree of adaptation of different variables. Muscle activity pattern was initially prominent under the more challenging conditions (HF, EC and EO; LF, EC) and diminished progressively to reach a steady state. At HF, the behavior of CoM and CoP was almost invariant. The time-constant of EMG adaptation was shorter for TA than for Sol. With EC, the adaptation index showed a larger decay in the TA than Sol activity at the end of the balancing trial, pointing to a different role of the two muscles in the adaptation process. At LF, CoM and CoP oscillations increased during the balancing trial to match the platform translations. This occurred regardless of the different EMG patterns under EO and EC. Contrary to CoM and CoP, the adaptation of the muscle activities had a similar time-course at both HF and LF, in spite of the two frequencies implying a different number of oscillation cycles. During adaptation, under critical balancing conditions (HF), postural muscle activity is tuned to that sufficient for keeping CoM within narrow limits. On the contrary, at LF, when vision permits, a similar decreasing pattern of muscle activity parallels a progressive increase in CoM oscillation amplitude, and the adaptive balancing behavior shifts from the initially reactive behavior to one of passive riding the platform. Adaptive balance control would rely on on-line computation of risk of falling and sensory inflow, while minimizing balance challenge and muscle effort. The results from this study contribute to the understanding of plasticity of the balance control mechanisms under posture-challenging conditions.     

The structure of semantic person memory: evidence from semantic priming in person recognition

This paper reviews research on the structure of semantic person memory as examined with semantic priming. In this experimental paradigm, a familiarity decision on a target face or written name is usually faster when it is preceded by a related as compared to an unrelated prime. This effect has been shown to be relatively short lived and susceptible to interfering items. Moreover, semantic priming can cross stimulus domains, such that a written name can prime a target face and vice versa. However, it remains controversial whether representations of people are stored in associative networks based on co-occurrence, or in more abstract semantic categories. In line with prominent cognitive models of face recognition, which explain semantic priming by shared semantic information between prime and target, recent research demonstrated that priming could be obtained from purely categorically related, non-associated prime/target pairs. Although strategic processes, such as expectancy and retrospective matching likely contribute, there is also evidence for a non-strategic contribution to priming, presumably related to spreading activation. Finally, a semantic priming effect has been demonstrated in the N400 event-related potential (ERP) component, which may reflect facilitated access to semantic information. It is concluded that categorical relatedness is one organizing principle of semantic person memory.     

Health-Related Quality of Life is Associated with Positive Affect in Patients with Coronary Heart Disease Entering Cardiac Rehabilitation

Health-related quality of life (QoL) is an important and widely used outcome measure in cardiac populations. We examined the relationship between positive affect and health-related quality of life, controlling for traditional cardiovascular risk factors, clinical variables and negative affect. We further investigated the role of gender in this relationship given the well-known gender differences in cardiovascular health. We enrolled 746 patients with coronary heart disease (CHD) before they entered outpatient cardiac rehabilitation. All patients completed the Global Mood Scale and the SF-36 Health Survey. Positive affect was independently associated with mental (p < .001) and physical QoL (p < .001) after controlling for control variables. Gender moderated the relationship between positive affect and physical QoL (p = .009) but not mental QoL (p = .60). Positive affect was positively associated with physical QoL in men (p < .001) but not in women (p = .44). The health-related QoL of patients with CHD is associated with a person’s level of positive affect.     

Recall-to-reject: The effect of category cues on false recognition

Four experiments examined the effect of category cueing on recall-to-reject, one of the central memory-editing mechanisms thought to prevent the occurrence of false memories. When category names were used as retrieval cues, the typically observed false recognition effect was eliminated for semantically associated distractors (Experiment 1a) and, moreover, a reduction in the absolute level of the false alarm rate was found for phonologically associated distractors (Experiment 2a). In addition to the old/new-recognition data, analyses using multinomial models support the interpretation that category cueing was successful in increasing the probability of recall-to-reject (Experiments 1b and 2b). The results are in line with dual-process theories of recognition memory and provide further evidence for recall-to-reject in single item recognition. They demonstrate its potential to reduce false recognition even when explicit instructions are not given. In addition, the results demonstrate that the paradigm can give rise to side effects that oppose recall-to-reject. A simultaneous familiarity increase can explain why many studies failed to find evidence for recall-to-reject in terms of false alarm rates.     

Ageing faces in ageing minds: A review on the own-age bias in face recognition

Similar to the well-established own-race bias, participants are more accurate at remembering own- relative to other-age faces. An own-age bias (OAB) in face memory was demonstrated in participants older than approximately 5 years. Crucially, the OAB is modulated by contact—participants with substantial contact with other-age persons show either reduced or absent OAB effects. In line with a perceptual expertise account of the phenomenon, holistic processing of other-age faces is less efficient when tested with young adult versus child faces, and differential holistic processing may therefore reflect one mechanism contributing to the OAB. A possible additional contribution of sociocognitive factors to the OAB remains largely untested. Importantly, event-related brain potential studies suggest that the own-race and own-age biases are based on at least partly different mechanisms. Theoretical explanations for different group-based biases in face memory will need to consider these findings.     

Phonological abstraction without phonemes in speech perception

Recent evidence shows that listeners use abstract prelexical units in speech perception. Using the phenomenon of lexical retuning in speech processing, we ask whether those units are necessarily phonemic. Dutch listeners were exposed to a Dutch speaker producing ambiguous phones between the Dutch syllable-final allophones approximant [r] and dark [l]. These ambiguous phones replaced either final /r/ or final /l/ in words in a lexical-decision task. This differential exposure affected perception of ambiguous stimuli on the same allophone continuum in a subsequent phonetic-categorization test: Listeners exposed to ambiguous phones in /r/-final words were more likely to perceive test stimuli as /r/ than listeners with exposure in /l/-final words. This effect was not found for test stimuli on continua using other allophones of /r/ and /l/. These results confirm that listeners use phonological abstraction in speech perception. They also show that context-sensitive allophones can play a role in this process, and hence that context-insensitive phonemes are not necessary. We suggest there may be no one unit of perception.     

The fragile nature of the speech-perception deficit in dyslexia: natural vs synthetic speech

A number of studies reported that developmental dyslexics are impaired in speech perception, especially for speech signals consisting of rapid auditory transitions. These studies mostly made use of a categorical-perception task with synthetic-speech samples. In this study, we show that deficits in the perception of synthetic speech do not generalise to the perception of more naturally sounding speech, even if the same experimental paradigm is used. This contrasts with the assumption that dyslexics are impaired in the perception of rapid auditory transitions.     

Das Problem der Chronometerauswahl

On Choice of Time Metric. What criteria ought to be satisfied by those observable processes which, accompanied by a function assigning values to intervals of that processes, serve as the standard for measurement of time? In how far do the criteria which can reasonably be established admit of an unambigous definition of time metric? That are the questions to which I have addressed myself in the paper. Peter Janich has aimed at solving the problem with careful avoidance of any reference to physical theory. Although this paper owes a great deal to his ‘Protophysik der Zeit’, reasons will be ad-vanced that it is in principle impossible to give a foundation of time metric without any reference to physical theory. It follows that taking results of physical theory into account is unavoidable as far as a definite decision concerning the choice of time metric is aspired. At first sight reference to law-like assertions on the duration of temporal intervals appears to be paradoxical for it means to take something which originally ought to be submitted to experimental test as the standard for measurement. Poincaré is fairly conscious of this problem, yet explicitly acknowledges that there is a mutual relationship between definition of time metric and physical theory. It will be shown that this kind of mutual relationship which even might be termed as circular does not void physical theory of empirical content. Thus in the final part I am concerned to free the position which recommends reference to physical theory from its paradoxical image in order to advance a conventionalist account as a sceptical, but nevertheless fully satisfying solution.     

On the causes of compensation for coarticulation: evidence for phonological mediation

This study examined whether compensation for coarticulation in fricative-vowel syllables is phonologically mediated or a consequence of auditory processes. Smits (2001a) had shown that compensation occurs for anticipatory lip rounding in a fricative caused by a following rounded vowel in Dutch. In a first experiment, the possibility that compensation is due to general auditory processing was investigated using nonspeech sounds. These did not cause context effects akin to compensation for coarticulation, although nonspeech sounds influenced speech sound identification in an integrative fashion. In a second experiment, a possible phonological basis for compensation for coarticulation was assessed by using audiovisual speech. Visual displays, which induced the perception of a rounded vowel, also influenced compensation for anticipatory lip rounding in the fricative. These results indicate that compensation for anticipatory lip rounding in fricative-vowel syllables is phonologically mediated. This result is discussed in the light of other compensation-for-coarticulation findings and general theories of speech perception.