Discrimination tests of visually influenced syllables

In the McGurk effect, perception of audiovisually discrepant syllables can depend on auditory, visual, or a combination of audiovisual information. Undersome conditions, Vi8Ual information can override auditory information to the extent that identification judgments of a-visually influenced syllable can be as consistent as for an analogous audiovisually compatible syllable. This might indicate that visually influenced and analogous audiuvisually-compatible syllables-are-phictnetically equivalent. Experiments were designed to test this issue using a compelling visually influenced syllable in an AXB matching paradigm. Subjects were asked tomatch an audio syllable /val either to an audiovisually consistent syllable (audio /val-video /fa/) or an audiovisually discrepant syllable (audio /bs/-video ifa!). It was hypothesized that if the two audiovisual syllables were phonetically equivalent, then subjects should choose them equally often in the matching task. Results show, however, that subjects are more likely to match the audio /va/ to the audiovisually consistent /va/, suggesting differences in phonetic convincingness. Additional experiments further suggest that this preference is not based on a phonetically extraneous dimension or on noticeable relative audiovisual discrepancies.     

Discrimination of visually perceived intervals of time

The discrimination of short intervals of time, demarcated by a foveally presented spatially distinct double pulse of light, was studied under several conditions of pulse intensity, angular diameter, and duration. We defined temporal acuity as a measure of discrimination capacity in terms of d′ values. It is shown that the acuity mechanism uses largely integrated information—in the spatial and temporal domain, up to at least 56′ and 32 msec, respectively. Acuity increases slightly with increasing integrated pulse energy, but seems quite independent of the presence of an adapting field of appreciable brightness. Studies on the effect of the foveal site aimed at by the pulses of light have shown that temporal projections lead to significantly poorer acuity values than nasal projections. Monoptic and dichoptic stimulation, however, are fully equivalent.     

Analyzing single-case data with visually guided randomization tests

The valid use of a randomization test with single-case data typically involves the choice of a test statistic prior to gathering data. In situations in which it is difficult to anticipate the form of the effect, the early specification of the test statistic can be problematic. The purpose of this paper is to demonstrate methods that will allow single-case researchers to conduct valid randomization tests in situations in which they wish to delay the specification of the test statistic until the data have been observed. A concrete example is given to motivate the use, explicate the logic, and demonstrate the conduct of this method.     

Orthographic vs. phonologic syllables in handwriting production

French children program the words they write syllable by syllable. We examined whether the syllable the children use to segment words is determined phonologically (i.e., is derived from speech production processes) or orthographically. Third, 4th and 5th graders wrote on a digitiser words that were mono-syllables phonologically (e.g. barque = [baRk]) but bi-syllables orthographically (e.g. barque = bar.que). These words were matched to words that were bi-syllables both phonologically and orthographically (e.g. balcon = [bal.kõ] and bal.con). The results on letter stroke duration and fluency yielded significant peaks at the syllable boundary for both types of words, indicating that the children use orthographic rather than phonological syllables as processing units to program the words they write.     

Processing the intensity of dichotic syllables

Subjects were required to match the intensity levels of the left- and right-ear members of dichotically presented nonsense syllables. When subjects matched the overall average intensities of a sequence of differing dichotic pairs no ear differences were observed. When repetitions of single dichotic pairs were matched right-ear syllables were judged louder than left-ear syllables. The results support a model predicting left-hemisphere superiority in a task permitting higher-level encoding of speech input.     

Identification of twins by spoken syllables

It is shown that the results of an experiment on speaker identification described by Whiteside and Rixon in 2000 seem to be contradictory and inconclusive. To investigate whether the experiment allows reliable conclusions, re-evaluation of their data using multiple regression techniques is proposed.     

Perceptual representations of phonotactically illegal syllables

Listeners often categorize phonotactically illegal sequences (e.g., /dla/ in English) as phonemically similar legal ones (e.g., /gla/). In an earlier investigation of such an effect in Japanese, Dehaene-Lambertz, Dupoux, and Gout (2000) did not observe a mismatch negativity in response to deviant, illegal sequences, and therefore argued that phonotactics constrain early perceptual processing. In the present study, using a priming paradigm, we compared the event-related potentials elicited by Legal targets (e.g., /gla/) preceded by (1) phonemically distinct Control primes (e.g., /kla/), (2) different tokens of Identity primes (e.g., /gla/), and (3) phonotactically Illegal Test primes (e.g., /dla/). Targets elicited a larger positivity 200–350 ms after onset when preceded by Illegal Test primes or phonemically distinct Control primes, as compared to Identity primes. Later portions of the waveforms (350–600 ms) did not differ for targets preceded by Identity and Illegal Test primes, and the similarity ratings also did not differ in these conditions. These data support a model of speech perception in which veridical representations of phoneme sequences are not only generated during processing, but also are maintained in a manner that affects perceptual processing of subsequent speech sounds.     

Three-month-olds' detection of alliteration in syllables

Using an auditory-preference procedure we found that 3-month-olds listened significantly longer to alliterative CVCs than to non-alliterative CVCs. This finding demonstrates that 3-month-olds are sensitive to syllable onsets and is discussed in relation to early speech perception and similar results found with 9-month-olds [Jusczyk, P. W., Goodman, M. B., & Baumann, A. (1999). Nine-month-olds' attention to sound similarities in syllables. Journal of Memory & Language, 40, 62-82].     

Short-term memory errors for spoken syllables are affected by the linguistic structure of the syllables

Three experiments on short-term serial memory for spoken syllables are reported. The stimuli were CVC (consonant-vowel-consonant) syllables in Experiment 1, CCVs in Experiment 2, and VCCs in Experiment 3. Analyses of subjects' errors showed that the phonemes within a syllable were not equally free to break apart and recombine. Certain groups of phonemes-the vowel-final consonant group of a CVC, the initial cluster of a CCV, and a vowel-liquid group within a VCC-tended to behave as units. These results are consistent with the view that syllables are coded in terms of an onset (initial consonant or cluster) and a rime (remainder). Errors in short-term memory for spoken syllables are affected by the linguistic structure of the syllables.     

Properties of memory for unattended spoken syllables

Whereas previous studies on memory for unattended speech have inadvertently included acoustic interference, the present study examines memory for unattended syllables during a silent period of 1, 5, or 10 s. The primary task was to read silently (Experiments 1-3) or whisper the reading (Experiment 4). Occasionally, when a light cue occurred, the subject was to recall the most recent spoken syllable, as well as the recent reading material. Memory for both the vowels and consonants of the syllables decreased across 10 s, confirming that auditory memory does decay in the absence of acoustic interference. However, the specific patterns of memory decay for vowels versus consonants depended on task demands, including the allocation of attention and the opportunity for subvocal coding. We suggest an account of performance that includes auditory sensory and phonetic memory codes with different properties, used in combination.     

The relative accessibility of phonemes and syllables

Previous research comparing detection times for syllables and for phonemes has consistently found that syllables are responded to faster than phonemes. This finding poses theoretical problems for strictly hierarchical models of speech recognition, in which smaller units should be able to be identified faster than larger units. However, inspection of the characteristics of previous experiments’ stimuli reveals that subjects have been able to respond to syllables on the basis of only a partial analysis of the stimulus. In the present experiment, five groups of subjects listened to identical stimulus material. Phoneme and syllable monitoring under standard conditions was compared with monitoring under conditions in which near matches of target and stimulus occurred on no-response trials. In the latter case, when subjects were forced to analyze each stimulus fully, phonemes were detected faster than syllables.     

Development of spatial concepts in visually deprived children.

110 blind children in Grades 2 through 12 were matched with sighted controls for age, sex, and verbal reasoning ability. Spatial reasoning was compared with nonspatial reasoning ability for the two groups. At each age level, blind children were inferior to sighted children on spatial reasoning, although the two groups did not differ on nonspatial reasoning. Data further support the likelihood that certain interactions with the perceptual environment may be crucial to specific aspects of cognitive functioning in humans.     

Visual space perception and visually directed action.

The results of two types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4 m-12 m). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric tasks.     

Identifiability of vowels and speakers from whispered syllables

In the present experiments, the effect of whisper register on speech perception was measured. We assessed listeners' abilities to identify 10 vowels in [hVd] context pronounced by 3 male and 3 female speakers in normal and whisper registers. Results showed 82% average identification accuracy in whisper mode, approximately a 10% falloff in identification accuracy from normally phonated speech. In both modes, significant confusions of [o] for [a] occurred, with some additional significant confusions occurring in whisper mode among vowels adjacent in F1/F2 space. We also assessed listeners' abilities to match whispered syllables with normally phonated ones by the same speaker. Each trial contained the matching syllable and two foils whispered by speakers of the same sex as the speaker of the target. Identification performance was significantly better than chance across subjects, speakers, and vowels, with no listener achieving better than 96% performance. Acoustic analyses measured potential cues to speaker identity independent of register.