Acoustic determinants of perceptual center (P-center) location

Morton, Marcus, and Frankish (1976) defined “perceptual center,” or “P-center,” as a neutral term to describe that which is regular in a perceptually regular sequence of speech sounds. This paper describes a paradigm for the determination of P-center location and the effect of various acoustic parameters on empirically determined P-center locations. It is shown that P-center location is affected by both initial consonant duration and, secondarily, subsequent vowel and consonant duration. A simple two-parameter model involving the duration of the whole stimulus is developed and gives good performance in predicting P-center location. The application of this model to continuous speech is demonstrated. It is suggested that there is little value in attempting to determine any single acoustic or articulatory correlate of P-center location, or in attempting to define P-center location absolutely in time. Rather, these results indicate that P-centers are a property of the whole stimulus and reflect properties of both the production and perception of speech.     

Lateral asymmetry of the scalp distribution of somatosensory evoked potential amplitude

Somatosensory potentials evoked by brief low-intensity electrical pulses delivered separately to the left and right index fingers were recorded from the scalp over the posterior half of the contralateral hemisphere in normal human subjects. In two experiments it was found that the scalp areas enclosed by 75 and 90% of maximum-amplitude isopotential contour lines of the early cortically generated complexes were more restricted over the left hemisphere. This asymmetrical evoked potential distribution supports the proposal by Semmes from her observations of brain-damaged patients that elementary somatosensory representation is focal in the left hemisphere and diffuse in the right.     

Hopping in a Gaussian distribution of energy states: Transition from dispersive to non-dispersive transport

Abstract

By means of Monte Carlo simulation techniques the relaxation of a packet of charge carriers migrating in a Gaussian density of states of width σ has been studied. The relaxation time determines the transition from dispersive to non-dispersive transport seen in a time-of-flight signal. For a 10 μm thick sample under a bias field of 10⁵ V cm^?1 the critical disorder parameter σ/kT turns out to be 4·4. Consistency with experimental results from polymers is found.     

Sensitivity to amplitude envelope rise time in infancy and vocabulary development at 3 years: A significant relationship

Here we report, for the first time, a relationship between sensitivity to amplitude envelope rise time in infants and their later vocabulary development. Recent research in auditory neuroscience has revealed that amplitude envelope rise time plays a mechanistic role in speech encoding. Accordingly, individual differences in infant discrimination of amplitude envelope rise times could be expected to relate to individual differences in language acquisition. A group of 50 infants taking part in a longitudinal study contributed rise time discrimination thresholds when aged 7 and 10 months, and their vocabulary development was measured at 3 years. Experimental measures of phonological sensitivity were also administered at 3 years. Linear mixed effect models taking rise time sensitivity as the dependent variable, and controlling for non‐verbal IQ, showed significant predictive effects for vocabulary at 3 years, but not for the phonological sensitivity measures. The significant longitudinal relationship between amplitude envelope rise time discrimination and vocabulary development suggests that early rise time discrimination abilities have an impact on speech processing by infants.     

Retinal location and its effect on the spatial distribution of visual attention

A series of studies tested for distractor compatibility effects across wide target/distractor distances (0.6 degree to 20 degrees of visual angle). The effects of precue condition, constant/varied target location, horizontal/vertical distractor distance, and foveal/peripheral presentation were studied. Results show strong compatibility effects across wide distances when distractors are at peripheral retinal locations. When both stimuli were presented at the same peripheral location in opposite hemifields, compatibility effects were evident within an area of at least 2.5 degrees of visual angle. In contrast, when foveally placed distractors were used, compatibility effects were found primarily with target letters positioned near. The findings suggest that distance effects are not homogeneous across retinal location.     

On the perception of speech from time-varying acoustic information: contributions of amplitude variation

The cyclic variation in the energy envelope of the speech signal results from the production of speech in syllables. This acoustic property is often identified as a source of information in the perception of syllable attributes, though spectral variation can also provide this information reliably. In the present study of the relative contributions of the energy and spectral envelopes in speech perception, we employed sinusoidal replicas of utterances, which permitted us to examine the roles of these acoustic properties in establishing or maintaining time-varying perceptual coherence. Three experiments were carried out to assess the independent perceptual effects of variation in sinusoidal amplitude and frequency, using sentence-length signals. In Experiment 1, we found that the fine grain of amplitude variation was not necessary for the perception of segmental and suprasegmental linguistic attributes; in Experiment 2, we found that amplitude was nonetheless effective in influencing syllable perception, and that in some circumstances it was crucial to segmental perception; in Experiment 3, we observed that coarse-grain amplitude variation, above all, proved to be extremely important in phonetic perception. We conclude that in perceiving sinusoidal replicas, the perceiver derives much from following the coherent pattern of frequency variation and gross signal energy, but probably derives rather little from tracking the precise details of the energy envelope. These findings encourage the view that the perceiver uses time-varying acoustic properties selectively in understanding speech.     

Location, location, location: the misprediction of satisfaction in housing lotteries

People tend to overestimate the emotional consequences of future life events, exhibiting an impact bias. The authors replicated the impact bias in a real-life context in which undergraduates were randomly assigned to dormitories (or "houses"). Participants appeared to focus on the wrong factors when imagining their future happiness in the houses. They placed far greater weight on highly variable physical features than on less variable social features in predicting their future happiness in each house, despite accurately recognizing that social features were more important than physical features when asked explicitly about the determinants of happiness. In Experiment 2, we found that this discrepancy emerged in part because participants exhibited an isolation effect, focusing too much on factors that distinguished between houses and not enough on factors that varied only slightly, such as social features.     

Scaling movement amplitude: adaptation of timing and amplitude control in a bimanual task

Participants traced two circles simultaneously and the diameter of one circle was scaled as the diameter of the other circle remained constant. When the scaled circle was larger, amplitude error shifted from overshooting to undershooting, while shifting from undershooting to overshooting when this circle was smaller. Asymmetric coordination was unstable when the left arm traced a circle larger than the right arm, yet stable when the left arm traced a smaller circle. When producing symmetric coordination and the left arm traced the larger circle, relative phase shifted by 30°, but a right arm lead predominated. When the left arm traced the smaller circle and symmetric coordination was required, a 30° shift in relative phase occurred, but hand lead changed from left to right. The modulation of movement amplitude and relative phase emerged simultaneously as a result of neural crosstalk effects linked to initial amplitude conditions and possibly visual feedback of the hands' motion.     

ADHD treatment in the 21st century: pushing the envelope

Required for optimal intervention for attention deficit hyperactivity disorder (ADHD) is evidence-based matching of child, treatment, and situation. The landmark Multimodal Treatment Study (MTA) of Children with ADHD documented the superiority of pharmacotherapy for the vast majority of children with ADHD. Although this study could not address the problem of the match directly, it is generating important leads for research on the use of psychosocial strategies to enhance the scope and durability of treatment gains while decreasing the risks attendant upon long-term use of medication. Given the inherent distinctions between pharmacological and psychosocial treatments, conclusive answers to questions about comparative efficacy will continue to elude scientist-practitioners. Needed next is research examining ways to improve outcomes beyond the effects of medication, using systematically tailored and sequenced psychosocial approaches and exploring new treatment targets, agents, and modalities. To illustrate, some emerging findings from an ongoing experience sampling study and implications for online therapy are discussed.     

句法预测对句子理解影响的眼动实验

实验采用眼动技术实时考察了句子阅读理解过程中的句法预测效应和并列句的结构表征特点。眼动数据分析发现：(1)有无句法预测没有明显影响名词短语区域的加工, 不同眼动指标差异不显著; (2)有无句法预测显著影响被试对包含暂时局部歧义的关键区和具有解歧作用的关键后区域的阅读理解, 首次注视时间、第一遍阅读时间、回视路径时间和第一遍回视率明显减少。眼动研究表明, 暂时局部歧义句子阅读理解过程中表现出明显的句法预测效应, 有句法预测降低了局部歧义区域和解歧区域早期和晚期加工的难度; 和英语的短语并列优先法则不同, 汉语并列句子的结构表征出现分离现象, 即短语并列和句子并列。     

Anticipation of tennis-shot direction from whole-body movement: The role of movement amplitude and dynamics

While recent studies indicate that observers are able to use dynamic information to anticipate whole-body actions like tennis shots, it is less clear whether the action’s amplitude may also allow for anticipation. We therefore examined the role of movement dynamics and amplitude for the anticipation of tennis-shot direction. In a previous study, movement dynamics and amplitude were separated from the kinematics of tennis players’ forehand groundstrokes. In the present study, these were manipulated and tennis shots were simulated. Three conditions were created in which shot-direction differences were either preserved or removed: Dynamics-Present–Amplitude-Present (D^PA^P), Dynamics-Present–Amplitude-Absent (D^PA^A), and Dynamics-Absent–Amplitude-Present (D^AA^P). Nineteen low-skill and 15 intermediate-skill tennis players watched the simulated shots and predicted shot direction from movements prior to ball-racket contact only. Percent of correctly predicted shots per condition was measured. On average, both groups’ performance was superior when the dynamics were present (the D^PA^P and D^PA^A conditions) compared to when it was absent (the D^AA^P condition). However, the intermediate-skill players performed above chance independent of amplitude differences in shots (i.e., both the D^PA^P and D^PA^A conditions), whereas the low-skill group only performed above chance when amplitude differences were absent (the D^PA^A condition). These results suggest that the movement’s dynamics but not their amplitude provides information from which tennis-shot direction can be anticipated. Furthermore, the successful extraction of dynamical information may be hampered by amplitude differences in a skill-dependent manner.     

The role of experience in location estimation: Target distributions shift location memory biases

Research based on the Category Adjustment model concluded that the spatial distribution of target locations does not influence location estimation responses [Huttenlocher, J., Hedges, L., Corrigan, B., & Crawford, L. E. (2004). Spatial categories and the estimation of location. Cognition, 93, 75–97]. This conflicts with earlier results showing that location estimation is biased relative to the spatial distribution of targets [Spencer, J. P., & Hund, A. M. (2002). Prototypes and particulars: Geometric and experience-dependent spatial categories. Journal of Experimental Psychology: General, 131, 16–37]. Here, we resolve this controversy by using a task based on Huttenlocher et al. (Experiment 4) with minor modifications to enhance our ability to detect experience-dependent effects. Results after the first block of trials replicate the pattern reported in Huttenlocher et al. After additional experience, however, participants showed biases that significantly shifted according to the target distributions. These results are consistent with the Dynamic Field Theory, an alternative theory of spatial cognition that integrates long-term memory traces across trials relative to the perceived structure of the task space.     

溃疡性结肠炎的诊断标准与诊断思维

溃疡性结肠炎的诊断条件包括临床表现、结肠镜改变、钡灌肠与肠黏膜组织学等,诊断标准应根据上述条件的不同组合分为疑诊与确诊,结肠镜与黏膜活检最为重要。强调在排除诊断基础上正确应用诊断标准。诊断成立后,应全面评估病情,特别是病变范围、严重度与活动性,以便合理地临床决策与预后判断,提高诊断水平。     

Location, location, location: how it affects the neighborhood (effect)

Reaction times in lexical decision are more sensitive to a words' length and orthographic-neighborhood density when the stimulus is presented to the left visual field (LVF) than to the right visual field (RVF). We claim that the length effect is equivalent to the neighborhood effect, and propose a novel explanation of why the LVF, but not the RVF, is sensitive to density, based on different firing rates of abstract-letter representations encoding letters falling in the LVF versus RVF. We support this proposal with a large-scale implemented model of lexical decision utilizing spiking units, which provides a reasonable fit to the data from the English Lexicon Project under simulated central presentation, while replicating the observed hemifield asymmetries under simulated lateralized presentation.