Is auditory discrimination mature by middle childhood? A study using time‐frequency analysis of mismatch responses from 7 years to adulthood

Behavioural and electrophysiological studies give differing impressions of when auditory discrimination is mature. Ability to discriminate frequency and speech contrasts reaches adult levels only around 12 years of age, yet an electrophysiological index of auditory discrimination, the mismatch negativity (MMN), is reported to be as large in children as in adults. Auditory ERPs were measured in 30 children (7 to 12 years), 23 teenagers (13 to 16 years) and 32 adults (35 to 56 years) in an oddball paradigm with tone or syllable stimuli. For each stimulus type, a standard stimulus (1000 Hz tone or syllable [ba]) occurred on 70% of trials, and one of two deviants (1030 or 1200 Hz tone, or syllables [da] or [bi]) equiprobably on the remaining trials. For the traditional MMN interval of 100–250 ms post-onset, size of mismatch responses increased with age, whereas the opposite trend was seen for an interval from 300 to 550 ms post-onset, corresponding to the late discriminative negativity (LDN). Time-frequency analysis of single trials revealed that the MMN resulted from phase-synchronization of oscillations in the theta (4–7 Hz) range, with greater synchronization in adults than children. Furthermore, the amount of synchronization was significantly correlated with frequency discrimination threshold. These results show that neurophysiological processes underlying auditory discrimination continue to develop through childhood and adolescence. Previous reports of adult-like MMN amplitudes in children may be artefactual results of using peak measurements when comparing groups that differ in variance.     

User perceptions and evaluations of short vibrotactile feedback

The objective of the present study was to provide a better understanding of the factors that influence discrimination and subjective assessment of vibrotactile feedbacks during active interaction with a touchscreen. Twenty-four participants were presented with 162 pairs of vibrotactile signals that varied in frequency (60 Hz, 130 Hz, 200 Hz), waveform (sine, square and triangle), and duration (around 123 ms for short and 163 ms for long). Participants had to complete three successive tasks: a dissimilarity task, a preference judgement task, and a resemblance (to push-buttons) judgement task. For the discrimination task, a MultiDimensional Scale analysis revealed: (1) a predominant role of frequency, (2) a role of duration for a given frequency, and (3) no role of waveform. An analysis of variance performed on the preference and resemblance data also point out the main role of the signal frequency. Finally, a correlation was found between preference and resemblance data, indicating that the participants tend to prefer signals judged to be similar to familiar tactile sensations.     

Processing emotional stimuli: Comparison of saccadic and manual choice-reaction times

We compared the speed of discrimination for emotional and neutral faces in four experiments, using a forced-choice saccadic and manual reaction time task. Unmasked, brief (20 ms) bilateral presentation of schematic (Exp. 1) or naturalistic (Exp. 2) emotional/neutral face pairs, led to shorter discrimination of emotional stimuli in saccadic localisation task. When the effect of interference from emotional stimuli is ruled out by showing a pairing of the emotional or neutral face with an outline face, faster saccadic discrimination was obtained for fearful facial expression only (Exp. 3). The manual discrimination reaction time was not significantly different for emotional versus neutral stimuli. To explore the absence of a manual RT effect we manipulated the stimulus duration (20 ms vs. 500 ms: Exp. 4). Faster saccadic discrimination of emotional stimuli was observed at both durations. For manual responses, emotional bias was observed only at the longest duration (500 ms). Overall, comparison of saccadic and manual responses shows that faster discrimination of emotional/neutral stimuli can be carried out within the oculomotor system. In addition, emotional stimuli are processed preferentially to neutral face stimuli.     

State and complexity-dependent symmetry identification of 2-dimensional patterns and evoked potentials

To analyse the influence of structural complexity of visual patterns and of an operationally defined cognitive state on evoked potentials some on--line closed--loop experiments were carried out. Symmetrical checkerboard patterns generated by means of Walsh functions were used as stimuli. The inherent symmetry should be recognized by the subjects. The state was defined on the basis of the spectral power density distribution of the EEG measured in the time interval of one second before the stimulus onset. The two state values were labeled by the state of alpha wave dominance and the state of non alpha wave dominance. According to the definition for the state of alpha wave dominance 70% of the whole spectral power must be contained in the frequency range from 8 Hz until 13 Hz at least. Otherwise the prestimulus EEG are labeled by the concept of non alpha wave state. The influence of the cognitive state and of the structural complexity on the evoked potentials has been verified experimentally. Significantly higher amplitudes of the evoked potentials in the time range of 140 ms until 200 ms after stimulus onset are due to higher complexity of the stimuli. The state of alpha wave dominance led to significantly stronger negativity of the evoked potentials in the range of 280 ms until 400 ms after stimulus onset.     

Auditory frequency generalization in the goldfish (Carassius auratus)

Auditory frequency generalization in the goldfish was studied at five points within the best hearing range through the use of classical respiratory conditioning. Each experimental group received single-stimulus conditioning sessions at one of five stimulus frequencies (100, 200, 400, 800, and 1600 Hz), and were subsequently tested for generalization at eight neighboring frequencies. All stimuli were presented 30 db above absolute threshold. Significant generalization decrements were found for all subjects. For the subjects conditioned in the range between 100 and 800 Hz, a nearly complete failure to generalize was found at one octave above and below the training frequency. The subjects conditioned at 1600 Hz produced relatively more flat gradients between 900 and 2000 Hz. The widths of the generalization gradients, expressed in Hz, increased as a power function of frequency with a slope greater than one.     

Buzzwords: early cortical responses to emotional words during reading

Electroencephalographic event-related brain potentials were recorded as subjects read, without further instruction, consecutively presented sequences of words. We varied the speed at which the sequences were presented (3 Hz and 1 Hz) and the words' emotional significance. Early event-related cortical responses during reading differentiated pleasant and unpleasant words from neutral words. Emotional words were associated with enhanced brain responses arising in predominantly left occipito-temporal areas 200 to 300 ms after presentation. Emotional words were also spontaneously better remembered than neutral words. The early cortical amplification was stable across 10 repetitions, providing evidence for robust enhancement of early visual processing of stimuli with learned emotional significance and underscoring the salience of emotional connotations during reading. During early processing stages, emotion-related enhancement of cortical activity along the dominant processing pathway is due to arousal, rather than valence of the stimuli. This enhancement may be driven by cortico-amygdaloid connections.     

Brief pitch-priming facilitates infants’ discrimination of pitch-evoking noise: Evidence from event-related potentials

Pitch is derived by the auditory system through complex spectrotemporal processing. Pitch extraction is thought to depend on both spectral cues arising from lower harmonics that are resolved by cochlear filters in the inner ear, and on temporal cues arising from the pattern of action potentials contained in the cochlear output. Adults are capable of extracting pitch in the absence of robust spectral cues, taking advantage of the temporal cues that remain. However, recent behavioral evidence suggests that infants have difficulty discriminating between stimuli with different pitches when resolvable spectral cues are absent. In the current experiments, we used the mismatch negativity (MMN) component of the event related potential derived from electroencephalographic (EEG) recordings to examine a cortical representation of pitch discrimination for iterated rippled noise (IRN) stimuli in 4- and 8-month-old infants. IRN stimuli are pitch-evoking sounds generated by repeatedly adding a segment of white noise to itself at a constant delay. We created IRN stimuli (delays of 5 and 6 ms creating pitch percepts of 200 and 167 Hz) and high-pass filtered them to remove all resolvable spectral pitch cues. In experiment 1, we did not find EEG evidence that infants could detect the change in the pitch of these IRN stimuli. However, in Experiment 2, after a brief period of pitch-priming during which we added a sine wave component to the IRN stimulus at its perceived pitch, infants did show significant MMN in response to pitch changes in the IRN stimuli with sine waves removed. This suggests that (1) infants can use temporal cues to process pitch, although such processing is not mature and (2) that a short amount of pitch-priming experience can alter pitch representations in auditory cortex during infancy.     

Is there low frequency vibrotactile temporal summation?

Reaction times of subjects to threshold vibratory stimuli of various durations and frequencies were measured simultaneously with the thresholds in order to test whether more time is needed for the detection of stimuli of long than short duration at threshold intensities. Vibratory stimuli of 20 or 150 Hz frequency and 50, 150, or 300 ms duration were applied to the back of the hand. Lower detection thresholds and longer reaction times were obtained for both 20 and 150 Hz vibration with increase of stimulus duration. The results suggest that temporal summation of high frequencies is due to energy integration , whereas at low frequencies probability summation explains better the threshold decrement.     

Noise increment detection in children 1 to 3 years of age

Studies using burst comparison procedures to examine age-related changes in intensity discrimination have reported that the ability to discriminate differences in intensity does not reach maturity until late childhood. In the present study, developmental changes in intensity discrimination were examined in 1- to 3-year-old children, using an increment detection paradigm. Children and adults detected increments in a continuous standard presented at three levels ranging from 35 to 55 dB SPL. Adults were also tested at lower levels of the standard in order to permit age comparisons at equivalent sensation levels. Standard stimuli were two-octave bands of noise centered at either 400 or 4000 Hz, and increments were 200 msec in duration. Discrimination performance improved significantly with both age and level of the standard. For all age groups, performance was significantly better for high- than for low-frequency stimuli, but frequency-dependent differences in increment thresholds did not vary reliably with age. Age differences were largest at low levels of the standard. At the highest level (approximately 30 dB nHL), children's difference limens for both low- and high-frequency noise bands were adultlike by 3 years of age. These results suggest that the developmental time course of increment detection is more rapid than that previously reported in burst comparison studies.     

Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength

The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.     

Speeding up an internal clock in children? Effects of visual flicker on subjective duration

Children of 3, 5, and 8 years of age were trained on a temporal bisection task where visual stimuli in the form of blue circles of 200 and 800 ms or 400 and 1600 ms duration, preceded by a 5-s white circle, served as the short and long standards. Following discrimination training between the standards, stimuli in the ranges 200-800 ms or 400-1600 ms were presented with the white circle either constant or flickering. Relative to the constant white circle, the flicker (1) increased the proportion of "long" responses (responses appropriate to the long standard), (2) shifted the psychophysical functions to the left, (3) decreased bisection point values, at all ages, and (4) did not systematically affect measures of temporal sensitivity, such as difference limen and Weber ratio. The results were consistent with the idea that the repetitive flicker had increased the speed of the pacemaker of an internal clock in children as young as 3 years. The "pacemaker speed" interpretation of the results was further strengthened by a greater effect of flicker in the 400/1600-ms condition than in the 200/800-ms condition.     

A "voice inversion effect?"

Voice is the carrier of speech but is also an "auditory face" rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a "voice inversion effect," by analogy to the classical "face inversion effect," which could support the hypothesis of a voice-specific module. Experiment 1 consisted of a gender identification task on two syllables pronounced by 90 speakers (boys, girls, men, and women). Experiment 2 consisted of a speaker discrimination task on pairs of syllables (8 men and 8 women). Experiment 3 consisted of an instrument discrimination task on pairs of melodies (8 string and 8 wind instruments). In all three experiments, stimuli were presented in 4 conditions: (1) no inversion; (2) temporal inversion (e.g., backwards speech); (3) frequency inversion centered around 4000 Hz; and (4) around 2500 Hz. Results indicated a significant decrease in performance caused by sound inversion, with a much stronger effect for frequency than for temporal inversion. Interestingly, although frequency inversion markedly affected timbre for both voices and instruments, subjects' performance was still above chance. However, performance at instrument discrimination was much higher than for voices, preventing comparison of inversion effects for voices vs. non-vocal stimuli. Additional experiments will be necessary to conclude on the existence of a possible "voice inversion effect."     

Auditory phase and frequency discrimination: a comparison of nine procedures

Two auditory discrimination tasks were thoroughly investigated: discrimination of frequency differences from a sinusoidal signal of 200 Hz and discrimination of differences in relative phase of mixed sinusoids of 200 Hz and 400 Hz. For each task psychometric functions were constructed for three observers, using nine different psychophysical measurement procedures. These procedures included yes-no, two-interval forced-choice, and various fixed- and variable-standard designs that investigators have used in recent years. The data showed wide ranges of apparent sensitivity. For frequency discrimination, models derived from signal detection theory for each psychophysical procedure seem to account for the performance differences. For phase discrimination the models do not account for the data. We conclude that for some discriminative continua the assumptions of signal detection theory are appropriate, and underlying sensitivity may be derived from raw data by appropriate transformations. For other continua the models of signal detection theory are probably inappropriate; we speculate that phase might be discriminable only on the basis of comparison or change and suggest some tests of our hypothesis.     

Brief pitch-priming facilitates infants’ discrimination of pitch-evoking noise: Evidence from event-related potentials

Pitch is derived by the auditory system through complex spectrotemporal processing. Pitch extraction is thought to depend on both spectral cues arising from lower harmonics that are resolved by cochlear filters in the inner ear, and on temporal cues arising from the pattern of action potentials contained in the cochlear output. Adults are capable of extracting pitch in the absence of robust spectral cues, taking advantage of the temporal cues that remain. However, recent behavioral evidence suggests that infants have difficulty discriminating between stimuli with different pitches when resolvable spectral cues are absent. In the current experiments, we used the mismatch negativity (MMN) component of the event related potential derived from electroencephalographic (EEG) recordings to examine a cortical representation of pitch discrimination for iterated rippled noise (IRN) stimuli in 4- and 8-month-old infants. IRN stimuli are pitch-evoking sounds generated by repeatedly adding a segment of white noise to itself at a constant delay. We created IRN stimuli (delays of 5 and 6 ms creating pitch percepts of 200 and 167 Hz) and high-pass filtered them to remove all resolvable spectral pitch cues. In experiment 1, we did not find EEG evidence that infants could detect the change in the pitch of these IRN stimuli. However, in Experiment 2, after a brief period of pitch-priming during which we added a sine wave component to the IRN stimulus at its perceived pitch, infants did show significant MMN in response to pitch changes in the IRN stimuli with sine waves removed. This suggests that (1) infants can use temporal cues to process pitch, although such processing is not mature and (2) that a short amount of pitch-priming experience can alter pitch representations in auditory cortex during infancy.     

人类镜像系统参与音乐情绪的自动加工：来自EEG的证据

大脑中线电极诱发的μ抑制波(包括α和β频段)是人类镜像系统活动的电生理指标。尽管音乐情绪表现被认为是通过模仿个体的心理状态来实现的, 但是尚未有研究探讨人类镜像系统与音乐情绪加工的关系。本研究通过EEG技术, 采用跨通道情绪启动范式, 探究人类镜像系统是否参与和弦情绪的自动加工。愉悦或不愉悦的和弦启动情绪一致与不一致的目标面孔。行为结果显示, 被试对情绪一致面孔的反应显著快于情绪不一致面孔的反应。EEG结果显示, 在听觉刺激出现后的500~650 ms之间, 与情绪一致条件相比, 情绪不一致条件诱发了β频段的去同步化。在听觉刺激出现后的300~450 ms, 无论是情绪一致, 还是不一致条件, 都诱发了α频段的去同步化。源分析结果显示, μ抑制波主要出现在人类镜像系统的相关脑区。这些结果表明, 音乐情绪的自动加工与人类镜像系统的活动密切相关。     

Mechanisms of displacement discrimination with and without perceived movement

A nearby visual reference point improves displacement discrimination. This effect occurs regardless of the delay between successive displays. The delay can be varied from short delays (50 ms), where observers report perceived movement, to long delays (2,000 ms), where observers report no movement. The similarity of reference effects for such different delay conditions was investigated by testing the independence of reference and delay effects. The critical independence property is whether the spatial variables (displacement and separation from the visual reference) combine independently of the temporal variable (delay). This kind of independence did not hold for displacement discrimination at delays of 50 ms and 2,000 ms. A further experiment tested for the independence property at delays of 500 ms and 4,000 ms, where observers reported no perceived movement. For these longer delays, the property was satisfied. These results are discussed using the general concept of a psychophysical mechanism. Such a mechanism combines the effects of several stimulus variables into a single mediating representation. By this analysis, at least two mechanisms must mediate the reference effect on displacement discrimination, one for delays of 200 ms and less and another for delays of 500 ms and more.     

Is there a mutual relationship between opposite attentional biases underlying anxiety?

Current models that account for attentional processes in anxiety have proposed that high-trait anxious individuals are characterized by a hypervigilant-avoidant pattern of attentional biases to threat. We adopted a laboratory conditioning procedure to induce concomitant hypervigilance and avoidance to threat, emphasizing a putative relationship between lower-level reactive and upper-level controlled attentional mechanisms as the core account of attentional processes involved in the development and maintenance of anxiety. Eighty high- and low-trait anxious participants underwent Pavlovian conditioning to a human face. Eye tracking was used to monitor attentional changes to the conditioned stimulus (CS+) face and the neutral stimulus (CS-) face, presented at 200, 500, and 800 ms durations. The high-anxious participants developed the expected attentional bias toward the CS+ at 200 ms presentation time and attentional avoidance at 500 and 800 ms durations. Hypervigilance to aversive stimuli at 200 ms and later avoidance to the same stimuli at 500 and 800 ms were associated with higher levels of galvanic skin conductance to the CS+. The low-anxious individuals developed the opposite attentional pattern with an initial tendency to orient attention away from the aversive stimuli in the 200 ms condition and to orient attention toward aversive stimuli in the remaining time. The differential modulation between hypervigilance and avoidance elicited in the two groups by the conditioning procedure suggests that vulnerability to anxiety is characterized by a latent relationship between diverse attentional mechanisms. Within this relationship, hypervigilance and avoidance to threat operate at different stages of information processing suggesting fuzzy boundaries between early reactive and later-strategic processing of threat.     

Is poor frequency modulation detection linked to literacy problems? A comparison of specific reading disability and mild to moderate sensorineural hearing loss

Specific reading disability (SRD) is now widely recognised as often being caused by phonological processing problems, affecting analysis of spoken as well as written language. According to one theoretical account, these phonological problems are due to low-level problems in auditory perception of dynamic acoustic cues. Evidence for this has come from studies showing poor discrimination of frequency-modulated from unmodulated tones. We measured frequency modulation detection limens (FMDLs) in 16 children with specific reading disability (SRD group), 16 children with mild to moderate hearing loss (SNH group) and 16 age-matched controls (CA group) aged 8-14. To obtain information about possible mechanisms used in frequency modulation detection, FMDLs were measured at modulation rates of 2 and 20 Hz, both in the absence and the presence of amplitude modulation, intended to force listeners to rely, if possible, upon phase-locking cues. Although both the SNH and SRD groups showed a trend for elevated FMDLs at both 2 and 20 Hz, these differences reached statistical significance for the SNH group alone. However, the SNH group had no evidence of literacy impairments. This study thus shows that impairments in perceiving dynamically modulated auditory stimuli do not necessarily lead to difficulty in learning to read.     

Anchor effects on the discrimination of pitch

Two experiments considered the effects of introducing an extreme stimulus (anchor) upon the differential perception of tonal stimuli. In the first experiment, in which Ss rated series stimuli from 1,000 to 2,000 Hz or from 2,000 to 3,000 Hz, the presence of a 750-Hz anchor apparently disrupted discrimination. A second experiment involved testing for a difference threshold (method of limits) in which the standard was a tone of 1,500 Hz. The uncertainty interval (Iu) was larger when the interval between paired stimulus presentations was filled with a 750-Hz tone, again suggesting that discrimination is impaired by the introduction of a low-frequency anchor. Results are discussed in terms of theories relating range extent and discriminability.     

Assessing crossmodal matching of abstract auditory and visual stimuli in posterior superior temporal sulcus with MEG

Associating crossmodal auditory and visual stimuli is an important component of perception, with the posterior superior temporal sulcus (pSTS) hypothesized to support this. However, recent evidence has argued that the pSTS serves to associate two stimuli irrespective of modality. To examine the contribution of pSTS to crossmodal recognition, participants (N = 13) learned 12 abstract, non-linguistic pairs of stimuli over 3 weeks. These paired associates comprised four types: auditory–visual (AV), auditory–auditory (AA), visual–auditory (VA), and visual–visual (VV). At week four, participants were scanned using magnetoencephalography (MEG) while performing a correct/incorrect judgment on pairs of items. Using an implementation of synthetic aperture magnetometry that computes real statistics across trials (SAMspm), we directly contrasted crossmodal (AV and VA) with unimodal (AA and VV) pairs from stimulus-onset to 2 s in theta (4–8 Hz), alpha (9–15 Hz), beta (16–30 Hz), and gamma (31–50 Hz) frequencies. We found pSTS showed greater desynchronization in the beta frequency for crossmodal compared with unimodal trials, suggesting greater activity during the crossmodal pairs, which was not influenced by congruency of the paired stimuli. Using a sliding window SAM analysis, we found the timing of this difference began in a window from 250 to 750 ms after stimulus-onset. Further, when we directly contrasted all sub-types of paired associates from stimulus-onset to 2 s, we found that pSTS seemed to respond to dynamic, auditory stimuli, rather than crossmodal stimuli per se. These findings support an early role for pSTS in the processing of dynamic, auditory stimuli, and do not support claims that pSTS is responsible for associating two stimuli irrespective of their modality.