Correlation between EEG and auditory perceptual measures in auditory agnosia

We describe a child who acquired a gradual sustained speech deficit for which no specific etiology was found, and who had an associated epileptogenic abnormality on EEG. Assessment of auditory perceptual skills and receptive language confirmed that gradual parallel improvement occurred with the EEG after therapeutic anticonvulsant blood levels were obtained. Prospective trials of anticonvulsant drugs in conjunction with serial measures of central auditory abilities are necessary to establish their value in the management of the linguistic deficit in children with auditory agnosia.     

Intellectual and perceptual correlates of reading disabilities

This study investigated the psychometric configurations on the WICS and Bender-Gestalt for primary grade pupils with reading problems. Pattern analysis provided virtually no clues as to the nature or extent of reading disability, either for the group as a whole or within a single grade.     

Late maturation of auditory perceptual learning

Adults can improve their performance on many perceptual tasks with training, but when does the response to training become mature? To investigate this question, we trained 11‐year‐olds, 14‐year‐olds and adults on a basic auditory task (temporal‐interval discrimination) using a multiple‐session training regimen known to be effective for adults. The adolescents all began with performance in the adult range. However, while all of the adults improved across sessions, none of the 11‐year‐olds and only half of the 14‐year‐olds did. The adolescents who failed to learn did so even though the 10‐session training regimen provided twice the number of sessions required by adults to reach asymptotic performance. Further, over the course of each session, the performance of the adults was stable but that of the adolescents, including those who learned, deteriorated. These results demonstrate that the processes that underlie perceptual learning can continue to develop well into adolescence.     

Some articulatory correlates of perceptual isochrony

Given sequences of digits with temporally equidistant acoustic onsets, listeners do not perceive them as isochronous (Morton, Marcus, & Frankish, 1976). In order for the sequences to be perceptually isochronous, systematic departures from acoustic isochrony must be introduced. These acoustic departures are precisely those that talkers generate when asked to produce an isochronous sequence (Fowler, 1979), suggesting that listeners judge isochrony based on acoustic information about articulatory timing. The present experiment was an attempt to test directly whether perceptually isochronous sequences have isochronous articulatory correlates. Electromyographic potentials were recorded from the orbicularis oris muscle when speakers produced sequences of monosyllables “as if speaking in time to a metronome.” Sequences were devised so that lip-muscle activity was related to the syllable-initial consonant, the stressed vowel, or the stressed vowel and final consonant. Results indicate that isochronous muscular activity accompanies both isochronous and anisochronous acoustic signals produced under instructions to generate isochronous sequences. These results support an interpretation of the perceptual phenomenon reported by Morton et al. to the effect that listeners judge isochrony of the talker’s articulations as they are reflected in the acoustic signal.     

On the relation between auditory spatial attention and auditory perceptual asymmetries

Laterality investigators have typically interpreted any perceptual asymmetry as a direct expression of the functional organization of the brain. However, many other confounding factors, including the asymmetric distribution of attention, may also contribute to either the magnitude or the direction of any of these advantages. In two experiments, attention was manipulated in a dichotic listening paradigm by presenting a preexposural tone cue to the ear from which the subject was required to report. The time available to orient attention was manipulated by varying the time period between the onset of the cue and the onset of the trial (stimulus onset asynchrony, or SOA).Results indicated that a right ear advantage for the identification of verbal material obtained at a 150-msec SOA was almost completely eliminated at an SOA of 450 msec. In addition, the direction of the ear advantage for emotion identification was found to depend on task difficulty. A left ear advantage, apparent when task difficulty was minimal, was reversed to a right ear advantage when difficulty was increased. These data are taken as evidence that, when subjects are faced with a difficult dichotic task, there is a general tendency for right-handed subjects to bias their attention toward the right ear. Such a tendency is shown not only to have likely seriously compromised the results of past investigations of functional perceptual asymmetries but also to be inconsistent with previously proposed theories of dichotic listening performance.     

Multisensory-mediated auditory localization

Multisensory integration is a powerful mechanism for maximizing sensitivity to sensory events. We examined its effects on auditory localization in healthy human subjects. The specific objective was to test whether the relative intensity and location of a seemingly irrelevant visual stimulus would influence auditory localization in accordance with the inverse effectiveness and spatial rules of multisensory integration that have been developed from neurophysiological studies with animals [Stein and Meredith, 1993 The Merging of the Senses (Cambridge, MA: MIT Press)]. Subjects were asked to localize a sound in one condition in which a neutral visual stimulus was either above threshold (supra-threshold) or at threshold. In both cases the spatial disparity of the visual and auditory stimuli was systematically varied. The results reveal that stimulus salience is a critical factor in determining the effect of a neutral visual cue on auditory localization. Visual bias and, hence, perceptual translocation of the auditory stimulus appeared when the visual stimulus was supra-threshold, regardless of its location. However, this was not the case when the visual stimulus was at threshold. In this case, the influence of the visual cue was apparent only when the two cues were spatially coincident and resulted in an enhancement of stimulus localization. These data suggest that the brain uses multiple strategies to integrate multisensory information.     

On the relation between auditory spatial attention and auditory perceptual asymmetries.

Laterality investigators have typically interpreted any perceptual asymmetry as a direct expression of the functional organization of the brain. However, many other confounding factors, including the asymmetric distribution of attention, may also contribute to either the magnitude or the direction of any of these advantages. In two experiments, attention was manipulated in a dichotic listening paradigm by presenting a preexposural tone cue to the ear from which the subject was required to report. The time available to orient attention was manipulated by varying the time period between the onset of the cue and the onset of the trial (stimulus onset asynchrony, or SOA). Results indicated that a right ear advantage for the identification of verbal material obtained at a 150-msec SOA was almost completely eliminated at an SOA of 450 msec. In addition, the direction of the ear advantage for emotion identification was found to depend on task difficulty. A left ear advantage, apparent when task difficulty was minimal, was reversed to a right ear advantage when difficulty was increased. These data are taken as evidence that, when subjects are faced with a difficult dichotic task, there is a general tendency for right-handed subjects to bias their attention toward the right ear. Such a tendency is shown not only to have likely seriously compromised the results of past investigations of functional perceptual asymmetries but also to be inconsistent with previously proposed theories of dichotic listening performance.     

The problem of universals and its perceptual correlates

This paper deals with the philosophical questions which gave rise to the traditional realist theories of universals. The main thesis is that these same questions may also be interpreted as scientific-empirical questions. The study of these problems has begun only very recently and the relevance of the results for the traditional problem of intensional entities has only been remarked by few workers aware of the philosophical problem. The approach adopted here is that of regarding man as a perceptual system situated in an environment and showing certain capacities like perception of universals. The possible ways of access to these entities is discussed on the basis of some recent empirical findings related to perception. One conclusion is that in order to answer the basic philosophical question of how properties, particulars and propositions are perceived may be answered within the domains of science, accepting only the usual presuppositions used in it. Basically, such an approach sees the root of the problem in the great complexity of information processing involved in the actual perception of properties, particulars and propositions.     

Visual and auditory facilitation in auditory spatial localization

It has previously been shown that adults localize unseen auditory targets more accurately with their eyes open than closed. The interpretation usually proposed to explain this phenomenon is that auditory spatial information is referred or translated to a visual frame of reference. The present experiments show that the presence of an auditory reference point facilitates auditory localization judgements in the same manner as a visual reference point does. Although our results do not support the visual frame of reference hypothesis, they suggest that the auditory and the visual modalities are strongly linked in their localizing processes.     

Attentional and perceptual sources of the auditory attentional blink

When a rapid succession of auditory stimuli is listened to, processing of the second of two successive targets among fillers is often impaired, a phenomenon known as the attentional blink (AB). Three experiments were conducted to examine the role of filler items in modulating the size of the auditory AB, using a two-alternative forced choice discrimination paradigm. In the first experiment, dual-stream presentations in which low- and high-pitch items were separated by six semitones were tested. A transient deficit in reporting the probe was observed in the presence of fillers that was greater when fillers were in the same stream as the probe. In the absence of a filler, there was a residual deficit, but this was not related to the time lag between the target and the probe. In the second and third experiments, in which single-stream presentations were used, a typical AB was found in the presence of homogeneous fillers, but heterogeneous fillers tended to produce a greater deficit. In the absence of a filler, there was little or no evidence of a blink. The pattern of results suggests that other attentional and perceptual factors contribute to the blink.     

Response uncertainty and perceptual difficulty of auditory temporal patterns

Two qualitatively different sounds were used to generate256 different sequences of length8, and these sequences were presented to Ss at a rate of two stimuli per second. These sequences, when repeatedcontinuously,canbe grouped into20 fundame ntally different patterns, each having either2, 4, or8 distinguishably different starting points. Ss were required to listen and to be gin responding (with telegraph keys) in synchrony to the patterns when they were able. The point at which they began responding, the delay before responding, and errors after beginning responding were measured. The response uncertainty (variability of point of response for a given pattern), average delay, and average errors are all highly correlated, indicating that patterns which are easily organized are those which have few alternative modes of organization, and thus can be considered as simple, or good in the Gestalt sense.     

The neural correlates of conceptual and perceptual false recognition

False recognition, broadly defined as a claim to remember something that was not encountered previously, can arise for multiple reasons. For instance, a distinction can be made between conceptual false recognition (i.e., false alarms resulting from semantic or associative similarities between studied and tested items) and perceptual false recognition (i.e., false alarms resulting from physical similarities between studied and tested items). Although false recognition has been associated with frontal cortex activity, it is unclear whether this frontal activity can be modulated by the precise relationship between studied and falsely remembered items. We used event-related fMRI to examine the neural basis of conceptual compared with perceptual false recognition. Results revealed preferential activity in multiple frontal cortex regions during conceptual false recognition, which likely reflected increased semantic processing during conceptual (but not perceptual) memory errors. These results extend recent reports that different types of false recognition can rely on dissociable neural substrates, and they indicate that the frontal activity that is often observed during false compared with true recognition can be modulated by the relationship between studied and tested items.