Primacy of dimensions in vibrotactile perception: an evaluation of early holistic models.

Early holistic models of perception presume that stimuli composed of interacting dimensions can be experienced initially as undifferentiated. This view, formalized through recourse to a Euclidean geometry of perceptual space, predicts that the orientation of axes used to create stimulus sets is unimportant to performance in speeded classification. We tested this idea by using the interacting vibrotactile dimensions of pitch and loudness. Despite perceivers' relatively poor experience with these dimensions, we showed that the orientation corresponding to pitch and loudness was unique in vibrotactile perceptual space; subjects classified stimuli more efficiently at this orientation than at other orientations. Certain holistic models also claim that when stimulus differences are small, perceivers can recognize change without distinguishing the kind of change. We tested this idea by using a signal detection analysis of unspeeded same-different decisions. We found that subjects' ability to notice the kind of change equaled their ability to notice the change alone. In view of these results, which indicate that pitch and loudness are primary in vibrotactile perception, we detail a new conception of dimensional interaction.     

Dimensional interactions in vibrotactile information processing

The effect of irrelevant dimensional variation on the processing of vibrotactile stimuli was measured. Six observers performed a speeded classification task with stimuli varying along the dimensions of pitch and loudness. Choice reaction times were obtained for stimuli differing on one dimension alone, on two correlated dimensions, or on two orthogonally varied dimensions. Compared to one-dimension performance, reaction times were faster in the correlated condition and slower in the orthogonal condition. In general, these findings agreed with similar experiments in other modalities, with the exception that the effects in this study tended to be stronger for cases in which loudness, rather than pitch, was the relevant dimension. The results are explained in terms of the integrality of pitch and loudness and of the relative discriminability of dimensions.     

Potential perceptual bases for successful use of a vibrotactile speech perception aid

This paper examines the possibility that perception of vibrotactile speech stimuli is enhanced in adults with early and life-long use of hearing aids. We present evidence that vibrotactile aid benefit in adults is directly related to the age at which the hearing aid was fitted and the duration of its use. The stimulus mechanism responsible for this effect is hypothesized to be long-term vibrotactile stimulation by high powered hearing aids. We speculate on possible mechanisms for enhanced vibrotactile speech perception as the result of hearing aid use: (1) long-term experience receiving degraded or impoverished speech stimuli results in a speech processing system that is more effective for novel stimuli, independent of perceptual modality; and/or (2) long-term sensory/perceptual experience causes neural changes that result in more effective delivery of speech information via somatosensory pathways.     

On cross-modal similarity: the perceptual structure of pitch, loudness, and brightness

Examined how pitch and loudness correspond to brightness. In the Experiment 1, 16 Ss identified which of 2 lights more resembled each of 16 tones; in Experiment 2, 8 of the same 16 Ss rated the similarity of lights to lights, tones to tones, and lights to tones. (1) Pitch and loudness both contributed to cross-modal similarity, but for most Ss pitch contributed more. (2) Individuals differed as to whether pitch or loudness contributed more; these differences were consistent across matching and similarity scaling. (3) Cross-modal similarity depended largely on relative stimulus values. (4) Multidimensional scaling revealed 2 perceptual dimensions, loudness and pitch, with brightness common to both. A simple quantitative model can describe the cross-modal comparisons, compatible with the view that perceptual similarity may be characterized through a malleable spatial representation that is multimodal as well as multidimensional.     

Hard and soft interacting dimensions: differential effects of dual context on classification

In this article, we extend Garner's speeded classification procedure to investigate processes underlying the interaction of the auditory dimensions pitch, loudness, and timbre. In the experiments reported here, subjects classified attributes on these three auditory dimensions. Our extended procedure, called multiclass, is based conceptually on our model of how such dimensions interact; the model explains the perception of attributes from an attended dimension through the action of contextual constraints created by variation along an unattended dimension. Two forms of context are present simultaneously in each multiclass task: intraclass context, variation along the unattended dimension that interferes with the classification of attributes, and redundant context, variation along the unattended dimension that enhances classification. We find that such dual-context situations reliably distinguish two kinds of interacting dimensions. Subjects classifying hard dimensions, here pitch and timbre, resist the ill effects of intraclass context and reap gains from redundant context. Subjects classifying soft dimensions, here loudness, show interference because the attributes are veiled perceptually in dual context. These findings, we argue, demonstrate the power of the multiclass procedure and fit well our view that dimensional interaction entails processing both at the level of the stimulus whole and at the level of stimulus attributes.     

Hard andsoft interacting dimensions: Differential effects of dual context on classification

In this article, we extend Garner’s speeded classification procedure to investigate processes underlying the interaction of the auditory dimensions pitch, loudness, and timbre. In the experiments reported here, subjects classified attributes on these three auditory dimensions. Our extended procedure, calledmulticlass, is based conceptually on our model of how such dimensions interact; the model explains the perception of attributes from an attended dimension through the action of contextual constraints created by variation along an unattended dimension. Two forms of context are present simultaneously in each multiclass task:intraclass context, variation along the unattended dimension that interferes with the classification of attributes, andredundant context, variation along the unattended dimension that enhances classification. We find that such dual-context situations reliably distinguish two kinds of interacting dimensions. Subjects classifying HARD dimensions, here pitch and timbre, resist the ill effects of intraclass.context and reap gains from redundant context. Subjects classifying SOFT dimensions, here loudness, show interference because the attributes are veiled perceptually in dual context, These findings, we argue, demonstrate the power of the multiclass procedure and fit well our view-that dimensional interaction entails processing both at the level of the stimulus whale and at the level of stimulus attributes.     

Auditory event files: Integrating auditory perception and action planning

The features of perceived objects are processed in distinct neural pathways, which call for mechanisms that integrate the distributed information into coherent representations (the binding problem). Recent studies of sequential effects have demonstrated feature binding not only in perception, but also across (visual) perception and action planning. We investigated whether comparable effects can be obtained in and across auditory perception and action. The results from two experiments revealed effects indicative of spontaneous integration of auditory features (pitch and loudness, pitch and location), as well as evidence for audio—manual stimulus—response integration. Even though integration takes place spontaneously, features related to task-relevant stimulus or response dimensions are more likely to be integrated. Moreover, integration seems to follow a temporal overlap principle, with features coded close in time being more likely to be bound together. Taken altogether, the findings are consistent with the idea of episodic event files integrating perception and action plans.     

Optional processes in similarity judgments

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configurai dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identifled-beforernandatory processes can be understood.     

Optional processes in similarity judgments.

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configural dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identified before mandatory processes can be understood.     

Vibrotactile--auditory interactions are post-perceptual

Vibrotactile stimuli can elicit compelling auditory sensations, even when sound energy levels are minimal and undetectable. It has previously been shown that subjects judge auditory tones embedded in white noise to be louder when they are accompanied by a vibrotactile stimulus of the same frequency. A first experiment replicated this result at four different levels of auditory stimulation (no tone, tone at detection threshold, tone at 5 dB above threshold, and tone at 10 dB above threshold). The presence of a vibrotactile stimulus induced an increase in the perceived loudness of auditory tones at three of the four values in this range. In two further experiments, a 2-interval forced-choice procedure was used to assess the nature of this cross-modal interaction. Subjects were biased when vibrotaction was applied in one interval, but applying vibrotaction in both intervals produced performance comparable to conditions without vibrotactile stimuli. This demonstrates that vibrotaction is sometimes ignored when judging the presence of an auditory tone. Hence the interaction between vibrotaction and audition does not appear to occur at an early perceptual level.     

Relative and Absolute Judgments of Speech Rate from Masked and Content-Standard Stimuli The Influence of Vocal Frequency and Intensity

In two previous studies, the perception of speech rate was found to be positively related to the vocal frequency and intensity of speech. In those studies, a single sample of spontaneous, content-masked speech was used to produce nine stimuli by factorially varying three levels of each vocal frequency and intensity, while controlling the actual speech rate of the stimuli. Participants were asked to judge each stimulus, preceded by a standard, “anchoring,” stimulus as to its speech rate, pitch, loudness, and duration. The purpose of the three studies reported here was to examine the generalizability of the previous findings by using stimuli that were nonmasked and/or were not preceded by an anchoring stimulus. In each study, nine speech stimuli were prepared, as described above, and participants were asked to make judgments about the rate, pitch, loudness, and duration of each stimulus. In the first study, the stimuli were masked but were not preceded by an anchoring stimulus. In the second study, participants listened to content-standard speech stimuli preceded by an anchoring stimulus. Finally, in the third study, content-standard stimuli without an anchoring stimulus were used. In addition, studies two and three used speech segments of a male and a female speaker. The findings from the three studies replicated the central findings of the previous studies. They suggest, in other words, that rate perception of speech is indeed influenced by vocal frequency and, to some extent, by intensity, and that these relationships are not materially altered by the speakers'gender.     

Pitch and loudness interact in auditory displays: can the data get lost in the map?

Many auditory displays use acoustic attributes such as frequency, intensity, and spectral content to represent different characteristics of multidimensional data. This study demonstrated a perceptual interaction between dynamic changes in pitch and loudness, as well as perceived asymmetries in directional acoustic change, that distorted the data relations represented in an auditory display. Three experiments showed that changes in loudness can influence pitch change, that changes in pitch can influence loudness change, and that increases in acoustic intensity are judged to change more than equivalent decreases. Within a sonification of stock market data, these characteristics created perceptual distortions in the data set. The results suggest that great care should be exercised when using lower level acoustic dimensions to represent multidimensional data.     

The shape of the vibrotactile loudness function: The effect of stimulus repetition and skin-contactor coupling

In the psychophysical literature describing the relationships between physical and psychological magnitudes, as physical intensity increases, perceived intensity often grows much faster near threshold than at higher levels. In this laboratory, however, the loudness curve for sinusoidal vibrotactile stimuli was best fit by a single-limbed function rather than by the expected two-limbed function. In the present study, we measured the growth of vibrotactile loudness of 250-Hz sinusoidal stimuli by the method of absolute magnitude estimation to explore the source of the one- versus two-limbed discrepancy. The number of times that the stimulus was presented was varied, as well as whether the stimulator contacted the skin with constant force or constant penetration. Neither of these manipulations affected the shape of the loudness function consistently. Number of repetitions influenced the shapes of the magnitude estimation functions, but only for a few individuals. Skin-contactor coupling did not affect the shapes of the functions, although the absolute level (vibrotactile loudness) was consistently greater for constant indentation.     

Perceptual organization of acoustic stimuli by budgerigars (Melopsittacus undulatus): I. Pure tones

A new combination of operant conditioning and psychophysical scaling procedures was used to study auditory perception in a small bird. In a same-different discrimination task, budgerigars learned to discriminate among pure tones that varied along one or more acoustic dimensions. Response latencies were used to generate a matrix of interstimulus similarities. Multidimensional scaling procedures were used to arrange these acoustic stimuli in a multidimensional space that supposedly reflects the bird's perceptual organization. For tones that varied in intensity, duration, and frequency simultaneously, budgerigars were much more sensitive to frequency changes. From a set of tones that varied only in intensity, it was possible to calculate the growth of loudness with intensity for the budgerigar. For tones that varied only in frequency, budgerigars showed evidence of an "acoustic fovea" for frequency change in the spectral region of 2-4 kHz. Budgerigars and humans also differed in their perceptual grouping of tone sequences that rise, fall, or remain constant in pitch. Surprisingly, budgerigars were much less responsive to pitch contour than were humans.     

Disrupting perceptual grouping of face parts impairs holistic face processing

Face perception is widely believed to involve integration of facial features into a holistic perceptual unit, but the mechanisms underlying this integration are relatively unknown. We examined whether perceptual grouping cues influence a classic marker of holistic face perception, the “composite-face effect.” Participants made same–different judgments about a cued part of sequentially presented chimeric faces, and holistic processing was indexed as the degree to which the task-irrelevant face halves impacted performance. Grouping was encouraged or discouraged by adjusting the backgrounds behind the face halves: Although the face halves were always aligned, their respective backgrounds could be misaligned and of different colors. Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1). This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3). These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.     

Anticipation and variation in visual content

This article is composed of three parts. In the first part of the article I take up a question raised by Susanna Siegel (Philosophical Review 115: 355–388, 2006a). Siegel has argued that subjects have the following anticipation: (PC) If S substantially changes her perspective on o, her visual phenomenology will change as a result of this change. She has left it an open question as to whether subjects anticipate a specific kind of change. I take up this question and answer it in the affirmative. By appealing to a widely held view of perceptual content, the view that we represent ‘factual’ properties in perception, I argue that (PC) can be refined as follows: (PC’) If S substantially changes her perspective on o, her visual phenomenology will present different views of o’s factual properties. In the second part of the article I argue that (PC’) implies that there are cases in which normal perceivers have different perceptual content under identical viewing conditions. The differences in perceptual content are due to differences in the determinacy of visual anticipation. I draw the conclusion that perceptual content is rich in the sense that it includes a unique contribution from individual perceivers. In the final part of the article, I discuss some open issues regarding the way in which (PC’) relates to the personal/sub-personal distinction, empirical models, and the distinction between perception and cognition.     

Perception of multidimensional stimuli: a differential-sensitivity account of cognitive processing and development.

A differential-sensitivity account of cognitive processing is described that emphasizes the development of perceptual sensitivity to object relations that are directly perceived. Four experiments are presented that investigate this account and compare it to the integrality-separability view of development and the view that younger children are nonselective in their processing of multidimensional stimuli. Results show that stimulus differences are more salient than identities (Expt. 1), younger as well as older children are highly selective in their perception and classify stimuli by separate dimensions (Expt. 2), differential sensitivity affects the perceived magnitude of stimulus differences (Expt. 3), and younger and older children perceive separate dimensions in speeded classifications (Expt. 4). The importance of considering individual patterns of responses in cognitive and developmental research is also demonstrated.     

刺激材料的整体性知觉对类别建构的影响

采用标准－匹配的实验程序,操纵刺激材料的空间整合性和知觉的整体性水平,探讨逐个呈现刺激材料时影响被试类别建构策略的根本原因。报告了3个实验,结果证明：逐个呈现并不一定会导致被试倾向于家族相似性归类;刺激材料的空间整合性不一定会影响被试的类别建构策略,空间整合和空间分离都可能出现家族相似性和单维归类倾向;刺激材料的整体性知觉水平对类别建构影响明显：知觉为分离则倾向于家族相似性分类;知觉为整体则倾向于单维分类。被试在实验可能采用分析性策略,然而材料的整体性知觉影响了分析的侧重点,从而对类别建构产生了非常重要的影响     

The Relationship Between Visual Illusion and Aesthetic Preference – an Attempt to Unify Experimental Phenomenology and Empirical Aesthetics

Experimental phenomenology has demonstrated that perception is much richer than stimulus. As is seen in color perception, one and the same stimulus provides more than several modes of appearance or perceptual dimensions. Similarly, there are various perceptual dimensions in form perception. Even a simple geometrical figure inducing visual illusion gives not only perceptual impressions of size, shape, slant, depth, and orientation, but also affective or aesthetic impressions. The present study reviews our experimental phenomenological work on visual illusion and experimental aesthetics, and examines how aesthetic preference is influenced by stimulus factors determining visual illusions including anomalous surface and transparency as well as geometrical illusion. Along with line figures producing geometrical illusions, illusory surface figures inducing neon color spreading and transparency effects were used as test patterns. Participants made both of psychophysical judgments and of aesthetic judgments for the same test pattern. Both of geometrical illusions and aesthetic preferences were found to change similarly as a function of stimulus variables such as the number of filling lines and the size ratio of the inner and outer figural components. Also, following specific stimulus variables such as lightness contrast ratio and spatial interval between inducing figural elements (so called ``packmen''), strong effects of color spreading and transparency were accompanied with strong preferences. It seems that the paradigm to investigate aesthetic phenomena along with perceptual dimensions is useful to bridge the gap between experimental phenomenology and experimental aesthetics.