The effects of lead stimulus and reflex stimulus modality on modulation of the blink reflex at very short, short, and long lead intervals

The blink reflex is modulated if a weak lead stimulus precedes the blink-eliciting stimulus. In two experiments, we examined the effects of the sensory modality of the lead and blink-eliciting stimuli on blink modulation. Acoustic, visual, or tactile lead stimuli were followed by an acoustic (Experiment 1) or an electrotactile (Experiment 2) blink-eliciting stimulus at lead intervals of -30, 0, 30, 60, 120, 240, 360, and 4,500 msec. The inhibition of blink magnitude at the short (60- to 360-msec) lead intervals and the facilitation of blink magnitude at the long (4,500-msec) lead interval observed for each lead stimulus modality was relatively unaffected by the blink-eliciting stimulus modality. The facilitation of blink magnitude at the very short (-30- to 30-msec) lead intervals was dependent on the combination of the lead and the blink-eliciting stimulus modalities. Modality specific and nonspecific processes operate at different levels of perceptual processing.     

The role of duration and rapid temporal processing on the lateral perception of consonants and vowels

This study explored the extent to which rapid temporal processing and duration contribute to the right-ear advantage (REA) and presumably left-hemisphere processing for stop consonants and the lack of clear-cut laterality effects for vowels. Three sets of synthetic stimuli were constructed: consonant vowel stimuli [ba da ga bi di gi bu du gu] of 300 msec duration (full stimuli) and two shortened stimuli consisting either of a noise burst and 40-msec transitions (40-msec stimuli), or a noise burst and 20-msec transitions (20-msec stimuli). Stimuli were presented dichotically for consonant, vowel, and syllable identification. Results indicated a significant REA for consonants in the full and 40-msec conditions and a non-significant REA in the 20-msec condition. Nevertheless, the magnitude of laterality did not change across the three conditions. These results suggest that although transition information including duration contributes to lateralization for stop consonants, it is the presence of abrupt onsets which crucially determines lateralized processing. For vowels, there was a significant REA only in the full stimulus condition, and a significant decrement in the magnitude of the laterality effect in the two shortened stimulus conditions. These results suggest that for vowel perception, it is the nature of the acoustic cue used for phonetic identification and not duration that seems to be the critical determinant of lateralization effects.     

Short-lived auditory memory for pitch

The effect of a stimulus suffix on immediate serial recall of lists of tones was assessed with 50- and 350-msec complex tones. Although recency effects were not found under the control conditions, the addition of a stimulus suffix significantly degraded recall at the final serial position for both stimulus durations. The implications of these results for models of auditory memory and speech perception are discussed.     

Precategorical acoustic storage and postcategorical lexical storage

A variety of experimental findings have indicated that a system of precategorical acoustic storage is responsible for the recency effect obtained in the immediate serial recall of sequences of digits, consonants, or syllables. This study investigated whether such findings could be generalized to the recall of sequences of words. Experiment 1 showed that phonemic similarity among a sequence of words failed to reduce the modality effect or the recency effect. Experiment 2 demonstrated that this finding was not attributable to a failure to control the phonemic properties of the stimulus material. Experiment 3 showed that the stimulus suffix effect obtained with sequences of words was not affected by the acoustic similarity between the list items and the stimulus suffix. Finally, Experiment 4 demonstrated that phonemic similarity among a sequence of words failed to reduce the stimulus suffix effect. These results were explained by extending the original model of short-term memory to incorporate a system of postcategorical lexical storage.     

Phonemic confusability,precategorical acoustic storage,and the suffix effect

Ss attempted ordered recall of acoustically presented strings of seven consonant-vowel syllables. In a control condition, each string was followed by a tone in presentation, while in the experimental (suffix) conditions, a verbal syllable followed the last to-be-remembered item. The independent variable was the phonemic similarity between the verbal suffix and the memory stimuli Although the verbal syllables produced a large suffix effect as compared with the control condition, and although more errors were made overall when similarity was high, the degree to which the verbal suffix items reduced the recency advantage at the end of the series was independent of their phonemic similarity to the stimuli. This independence was taken as support for a distinction between acoustic and articulatory coding.     

Hearing by eye

Recent work on integration of auditory and visual information during speech perception has indicated that adults are surprisingly good at, and rely extensively on, lip reading. The conceptual status of lip read information is of interest: such information is at the same time both visual and phonological. Three experiments investigated the nature of short term coding of lip read information in hearing subjects. The first experiment used asynchronous visual and auditory information and showed that a subject's ability to repeat words, when heard speech lagged lip movements, was unaffected by the lag duration, both quantitatively and qualitatively. This suggests that lip read information is immediately recoded into a durable code. An experiment on serial recall of lip read items showed a serial position curve containing a recency effect (characteristic of auditory but not visual input). It was then shown that an auditory suffix diminishes the recency effect obtained with lip read stimuli. These results are consistent with the hypothesis that seen speech, that is not heard, is encoded into a durable code which has some shared properties with heard speech. The results of the serial recall experiments are inconsistent with interpretations of the recency and suffix effects in terms of precategorical acoustic storage, for they demonstrate that recency and suffix effects can be supra-modal.     

Auditory evoked brain responses: Comparison of ON and OFF responses at long and short durations

Average evoked brain responses (EBRs) to three durations of one kilohertz pure-tone stimuli were computed from human scalp recordings. Stimuli of 25, 75, and 2,000 msec duration were each presented binaurally at each of eight equally spaced intensity levels, ranging from 58 to 86 dB SPL. EBRs computed immediately following presentation, and immediately following removal of the 2,000-msec-duration stimulus result in ON and OFF responses, respectively. EBRs computed immediately following presentation of the 25- and 75-msec-duration stimuli appear to be the result of the sum of separate responses to stimulus onset and offset. Computer-dissected ON and OFF EBRs to short-duration stimuli are very similar in waveform and amplitude to the responses evoked by the onset and offset, respectively, of the 2,000-msec duration stimulus. Dissected ON and OFF responses demonstrate linear amplitude-intensity functions in amplitude ranges similar to respective ON and OFF responses to 2,000-msec stimulation. The data suggest that ON and OFF responses are mediated by independent physiological mechanisms.     

Immediate and delayed recognition of sequentially presented random shapes.

Two experiments tested whether short-term memory accounts for the recency effect observed with rapid sequential presentation of nonverbal stimuli. Four random shapes were presented sequentially (with no interstimulus interval) on each trial at rates of 150 msec, 250 msec, 500 msec, and 1,000 msec per stimulus. Subsequent recognition varied positively with exposure duration, ranging from 57% at 150 msec to 77% at 1,000 msec. Two serial position effects were observed: a slight decrease in recognition accuracy for the first stimulus in each sequence and a large increase in recognition for the last stimulus in each sequence. The recency effect was not altered by an intervening 30-sec delay, an intervening 30-sec copying task, or an intervening 30-sec copying and counting task. Since neither visual nor verbal distractors altered recognition accuracy, it was suggested that all shapes were processed directly into long-term memory storage. It also was hypothesized that long-term storage of a nonverbal stimulus requires identification of a distinctive feature of the stimulus and that this process may continue for a brief period after actual stimulus offset.     

The effects of recoding and presentation format on recency and suffix effects

The primary linguistic theory of Shand and Klima (1981) hypothesizes that stimuli that cannot be directly processed without recoding are not in the primary linguistic mode of the subject and thus should lead to lesser recency and associated suffix effects. In three experiments, different normal hearing subjects learned to pair American Sign Language (ASL) stimuli, visual "quasivocables" (QVs), word-like letter strings, and auditory QVs with common English words. In the first experiment, the subjects were given sequences of ASL or QV stimuli and required to recall the associated words in strict serial order. In two other experiments involving auditory and visual presentation, respectively, subjects who had never been given paired associate training were required to recall the English words that had previously been associated with the ASL and QV stimuli, in a standard suffix paradigm. The results showed recency and suffix effects to be present only with auditorily presented QVs and words. Contrary to the predictions of the primary linguistic hypothesis, greater recency and larger suffix effects were present with the auditory QVs than with the auditory words, although the QVs were not primary linguistic and the task involved forced recoding. Previous results showing recency with ASL stimuli in normal subjects were not replicated. It is concluded that recency and suffix effects are not related either to the primary linguistic mode of the subject or to stimulus recoding, as we and Shand and Klima have defined them.     

On the locus of the stimulus suffix effect

Two experiments contrasted short-term memory and sensory memory (precategorical acoustic storage) explanations of the stimulus suffix effect. Experiment 1 attempted to interfere with recency recall by forcing subjects to encode nonverbal acoustic suffixes into a verbal, articulatory code. Subjects in this condition showed recall that was comparable to that of subjects who were told to ignore the suffixes. However, Experiment 2 showed that silently mouthed articulation of a suffix can produce interference on recall of recency items, although not as much as that produced by vocal articulation. The results are discussed in terms of current models of the stimulus suffix effect.     

Recency and suffix effects in pictures as a function of recall method

Two studies compared recency and suffix effects in pictures. In Experiment 1, which used strict serial recall, the recall curve for the control condition fell sharply until the final position when it exhibited a small but significant amount of recency. No suffix effects were present. In Experiment 2, a modified free recall condition exhibited a U-shaped serial position curve and significant recency. Picture and graphic suffixes led to small, reliable end-of-sequence suffix effects, but spoken suffixes did not. Thus pictures appear to lead to recency and suffix effects similar to those produced by static visual alphanumeric stimuli when strict serial recall is used. With a modified free recall procedure, recency is enhanced and suffix effects appear. The implications of the results with pictures and of differences between the two recall procedures are discussed with respect to literature in the area on pictures (Cohen, 1972) and American Sign Language (Krakow & Hanson, 1985; Shand & Klima, 1981). Additionally, some new methods of defining and analyzing recency, which are also applicable to primacy, are proposed and used in the paper to bring out more clearly the effects present.     

Is there a modality effect? Evidence for visual recency and suffix effects

In Experiment 1, four groups of 16 subjects performed ordered recall of six-syllable lists in both suffix and nonsuffix conditions. Sequential presentation of the lists varied for each group. In the auditory presentation, the syllables were delivered from one location only and were read aloud by the subjects. For the visual, spatially nondistributed presentation, the syllables appeared in one location only and were read silently. For visual, spatially distributed presentations, the syllables were spread out either vertically or horizontally and were read silently. Very robust recency and suffix effects were found in the auditory presentation, as well as in visual, spatially distributed presentations. In Experiment 2, 16 subjects performed ordered recall of visually presented lists with the items spread out vertically and conflicting spatial and temporal orders. A reliable recency effect was found for the final block of trials. In Experiment 3, 16 subjects performed ordered recall in the same conditions as in Experiment 2, except that they were instructed to recall the temporal order in which the spatial positions would be filled in. A bow-shaped curve and a strong recency effect were obtained.     

前分类声音存储器对声调和情绪韵律的加工

采用系列位置回忆任务, 探讨作为声调语言的汉语普通话中声调及情绪信息是否具有近因及后缀效应, 从而揭示同为超音段信息的声调和情绪韵律在前分类声音存储器(Precategorical Acoustic Storage, PAS)中是否具有单独的表征, 及该表征可能受到哪些因素的影响。实验一和二分别考察了声调是否具有近因和后缀效应, 实验三和四分别考察了情绪信息是否具有近因和后缀效应。实验结果发现两者均在PAS存储器中有单独的表征, 但这种表征会受到一些因素的影响, 且受影响的方式不一样。研究结果表明作为超音段信息的声调和情绪信息在表征上的不稳定性和脆弱性, 及在短时记忆加工过程中的特殊性。     

Providing a sensory basis for models of visual information acquisition

Our major goal is to account for some simple digit-recall data with a theory that integrates two models from two scientific traditions. Therandom-sampling model, founded in the memory and attention literature, holds that (1) stimulus features are randomly sampled throughout the course of stimulus presence and (2) proportion correct recall is equal to the ratio of sampled features to total features.The linear-filter model, founded in the vision and sensation literature, holds that the initial stages of the visual system act as a low-pass temporal filter on the input stimulus, resulting in a time-varyingsensory response in the nervous system. We report two experiments in which a variable-duration, masked, four-digit string had to be immediately recalled. Experiment 1 was designed principally to replicate past data confirming the basic random-sampling model. Like others, we were able to confirm the model only by endowing it with an additionalprocessing-delay assumption: that feature sampling does not begin until the stimulus has been physically present for some minimal duration. Experiment 2 was an extension of Experiment 1 in which the target stimulus was preceded, 250 msec prior to its onset, by a 50-msec pre-presentation ofthe same stimulus called aprime. The Experiment 2 results allowed the following conclusions. First, the initial processing delay found in Experiment 1 is immutably tied to stimulus onset; that is, if there are two stimulus onsets, separated even briefly in time, there are two associated processing delays. Second, processing rate is essentially unaffected by the prime’s presentation. Third, being presented with a 50-msec prime is equivalent, in terms of memory performance, to increasing unprimed stimulus duration by approximately 30 msec; the prime can thus said to beworth 30 msec of additional exposure duration. This third conclusion seems superficially paradoxical, in the sense that one would expect that having seen a 50-msec prime would be equivalent to increasing exposure duration byat least the same 50 msec. However, both the initial processing delays and the 30-msec prime’s worth are natural consequences of our theory that conjoins the random-sampling model with the linear-filter model.     

Acoustic memory and the perception of speech

The nature of acoustic memory and its relationship to the categorizing process in speech perception is investigated in three experiments on the serial recall of lists of syllables. The first study confirms previous reports that sequences comprising the syllables, bah, dah, and gah show neither enhanced retention when presented auditorily rather than visually, nor a recency effect—both occurred with sequences in which vowel sounds differed (bee, bih, boo). This was found not to be a simple vowel-consonant difference since acoustic memory effects did occur with consonant sequences that were acoustically more discriminable (sha, ma, ga and ash, am, ag). Further experiments used the stimulus suffix effect to provide evidence of acoustic memory, and showed (1), increasing the acoustic similarity of the set grossly impairs acoustic memory effects for vowels as well as consonants, and (2) such memory effects are no greater for steady-state vowels than for continuously changing diphthongs. It is concluded that the usefulness of the information that can be retrieved from acoustic memory depends on the acoustic similarity of the items in the list rather than on their phonetic class or whether or not they have “encoded” acoustic cues. These results question whether there is any psychological evidence for “encoded” speech sounds being categorized in ways different from other speech sounds.     

Reflex inhibition in humans: Sensitivity to brief silent periods in white noise

A white noise (60 dB SPL) was always present except for brief silent periods (“gaps”) which occurred just before an eyelid reflex was elicited in human volunteers by a brief innocuous shock to the forehead. In Experiment 1 (n=8), 10-msec gaps (“S1”) were given 40, 80, 120, 160, or 200 msec before the shock (“S2”). Compared with S2-alone trials, the reflex was inhibited by about 50% at intervals of 80 msec and beyond. Experiment 2 (n=12) first provided detection thresholds for gaps using a simple version of the method of limits: on average a gap of 5.4 msec duration was just detected. Then gaps of 0, 2, 4, 6, 8, and 10 msec were given in random order, each 100 msec before S2. The 4-msec stimulus was an effective inhibitor of the reflex, and inhibition further increased on to 6- and then to 8-msec durations. A comparison of the values obtained on reflex inhibition with the 5.4-msec threshold obtained with the conventional psycho-physical test reveals that in humans reflex inhibition provides an objective index of stimulus detection that is at least of sufficient sensitivity to warrant its clinical application. The steady increase in reflex inhibition as gap duration increased from 2 to 8 msec may be of significance for tracing the rate of decay of afferent stimulation following noise offset, as it presumably reflects the growing sensitivity to the resumption of the noise as the duration of the silent period is increased.     

Mechanisms of aural encoding: VII. Differences in consonant and vowel recall in a Peterson and Peterson short-term memory paradigm

Ss either saw or heard lists of three syllables which differed by their initial consonant phoneme or their final vowel phoneme. After 5 or 15 sec of mental arithmetic, Ss were required to recall the syllables. Following auditory presentation, vowels were recalled more accurately than consonants in all serial positions and at both delays. In addition, spoken consonants and vowels showed primacy and recency effects. Following visual presentation, consonants and vowels were recalled with equal accuracy at both delays, and no recency effects were observed. These data suggest that superior recall of vowels over consonants results from differential decay of these stimuli in an acoustic storage. These data are consistent with previous experiments showing that, during serial recall, the final vowels in a sequence are recalled more accurately than the final consonants.     

Recency and suffix effects in serial recall of musical stimuli

Auditory presentation of verbal items leads to larger recency effects in recall than visual presentation. This enhanced recency can be eliminated if a stimulus suffix (an irrelevant sound) follows the last item. Four experiments tested the hypothesis that recency and suffix effects in serial recall result from a speech-specific process. It was demonstrated that serial recall of musical notes played on a piano exhibited substantial recency effects. These recency effects were reduced when the list items were followed by either a piano chord or the word start. However, a white-noise suffix had no effect on recency. This pattern of data is consistent with current work on auditory perception and places constraints on theories of recency and suffix effects.     

The filled-duration illusion: The function of temporal and nontemporal set

Studies of the perception of time have demonstrated that large visual stimuli presented for the same duration as small stimuli will appear to have been presented longer. Two theoretical approaches have been offered to explain this effect. Both have emphasized the absolute amount of information in the stimulus. Thus, both would predict the effect when size is varied between sessions. The present study found no effect of size when size was held constant within sessions, but a substantial effect resulted when size was varied within sessions. Also examined was the range of stimulus durations used within a session. In one condition, patterns of various sizes were presented at 15, 30, or 45 msec, while in a second condition, the same patterns were presented to a different group of subjects at 15, 85, or 155 msec. The size effect was significantly reduced when longer time intervals were presented. A third group of subjects was shown patterns at even longer times but with a reduced range (155, 170, and 185 msec). Here the size effect was of equal magnitude to that of the 15-msec interval condition. The implications of these results are that current theoretical explanations of the filled-duration illusion rely on incorrect assumptions.     

Enhanced recency effects with changing-state and primary-linguistic stimuli

A number of explanations for the modality effect in immediate serial recall have been proposed. The auditory advantage for recall of recency items has been explained in terms of (1) the contributions of precategorical acoustic storage (PAS), (2) an advantage of changing-state over static stimuli, and (3) an advantage of primary-linguistic coding. Four experiments were conducted to evaluate these hypotheses. In the first, subjects viewed seven consecutive rectangles of different colors on a computer monitor. A small recency effect was obtained when the task was to recall the colors of the rectangles in order, with the size of the effect being independent of whether the rectangles remained stationary on the screen or moved in one of four directions. However, when the task was to recall the direction of movement of the rectangles, a larger recency effect was found. This pattern of results was interpreted as suggesting that recency effects are enhanced by changing-state stimulus information, but only when the changing-state information serves to identify the stimulus. Experiments 2 and 3 provided converging evidence by demonstrating an analogous recency advantage for changing-state visual stimuli that were somewhat different from those of Experiment 1. Experiment 4 demonstrated recency effects with synthesized speech stimuli that were substantially greater than were those found with the changing-state visual stimuli of the first three experiments. Implications of the results for the PAS, changing-state, and primary-linguistic hypotheses, as well as temporal-distinctiveness theories of recency, are discussed.