Measuring perceptual speed in complex everyday situations

This paper describes first results of the development of a new test to measure perceptual speed in everyday situations. The new items are best described as images depicting typical situations in everyday life, which have some picture elements in common. The pictures were presented to the subjects for a short time, and their task was to indicate which of 5 goal stimuli were present in the respective pictures seen before. In two studies, the scalability of the new items according to the Rasch model was investigated. In Study 1 data from 316 subjects with heterogeneous educational backgrounds were used in the empirical analysis. The results of Study 1 indicate that Rasch homogeneity and thus positive psychometric properties for the new test could be obtained. This result was further validated using a second sample (N = 198). The validation study replicates the results obtained in Study 1. These results represent a substantial condition sine qua non for following studies on the construct and criterion validity of the new test.     

Tactile perceptual task and field dependence-independence

Differential performance with both hands by 60 normal field-dependent or field-independent subjects who were solving Nebes' test, was assessed. No difference was found between hands, but a significant difference was noted for speed of performance between field-dependent and field-independent subjects.     

Acoustic determinants of perceptual center (P-center) location

Morton, Marcus, and Frankish (1976) defined “perceptual center,” or “P-center,” as a neutral term to describe that which is regular in a perceptually regular sequence of speech sounds. This paper describes a paradigm for the determination of P-center location and the effect of various acoustic parameters on empirically determined P-center locations. It is shown that P-center location is affected by both initial consonant duration and, secondarily, subsequent vowel and consonant duration. A simple two-parameter model involving the duration of the whole stimulus is developed and gives good performance in predicting P-center location. The application of this model to continuous speech is demonstrated. It is suggested that there is little value in attempting to determine any single acoustic or articulatory correlate of P-center location, or in attempting to define P-center location absolutely in time. Rather, these results indicate that P-centers are a property of the whole stimulus and reflect properties of both the production and perception of speech.     

Overestimation of base-rate differences in complex perceptual categories

The optimality of multidimensional perceptual categorization performance was examined for several base-rate ratios, for both integral and separable dimension stimuli, and for complex category structures. In all cases, the optimal decision bound was highly nonlinear. Observers completed several experimental sessions, and all analyses were performed at the single-observer level using a series of nested models derived from decision-bound theory (Maddox, 1995; Maddox & Ashby, 1993). In every condition, all observers were found to be sensitive to the base-rate manipulations, but the majority of observers appeared to overestimate the base-rate difference. These findings converge with those for cases in which the optimal decision bound was linear (Maddox, 1995) and suggest that base-rates are learned in a similar fashion regardless of the complexity of the optimal decision bound. Possible explanations for the consistent overestimate of the base-rate difference are discussed. Several continuous-valued analogues of Kruschke’s (1996) theory of base-rate learning with discrete-valued stimuli were tested. These models found some support, but in all cases were outperformed by a version of decision-bound theory that assumed accurate knowledge of the category structure and an overestimate of the base-rate difference.     

Levels of perceptual processing as a function of stimulus material and spatial location

Craik and Lockhart (1972) have proposed a framework for human memory research which is based on levels of processing. Most of the studies which support this approach have been concerned with comparing structural vs. semantic tasks. The present paper extends the levels of processing approach to earlier stages of processing and emphasizes levels ofperceptual processing. It is suggested that depth of perceptual processing depends on the nature of the stimulus material. Neisser’s (1967) theory of preattentive mechanisms and focal attention is shown to be a theory of levels of perceptual processing. Differences in the nature in which these two processes operates are discussed.     

Object location memory: The interplay of multiple representations

This article reports three experiments in which the representational nature of human object location memory was studied. The results show that multiple frames of reference can be used to encode the spatial relationships among objects. Depending on their dominancy, availability, and validity, these multiple representations interact to determine memory performance. Specifically, representations that are automatically encoded and extensively practiced are more dominant, and their availability improves performance when they are valid. On the other hand, when the dominant representations are available but invalid, people may have to resort to the less dominant representations. As a result, the availability of these dominant but invalid representations can actually hurt performance, due to interference. If these interfering representations are eliminated, the performance is again improved. The implications of these findings for general human spatial cognition are discussed.     

Facultative and inhibitory effects of location and frequency cues: Evidence of a modulation in perceptual sensitivity

The possibility that facilitative and inhibitory effects of auditory cues result because of a modulation in perceptual sensitivity was examined. Listeners were presented with a cue followed by a target, with the time period between the two varied at stimulus onset asynchronies (SOAs) of 150,450, or 750 msec. In two conditions, the cue and target were either the same or different in location or frequency. In both conditions, listeners were required to identify the rise time of the target. Whereas the cue was presented in isolation, the target was presented in a wide-band noise background such that the required discrimination was made relatively difficult. In both conditions, a facilitative effect was apparent at the 150-msec SOA and an inhibitory effect was apparent at the 750-msec SOA for both accuracy and response time measures of performance. That these results were apparent for a judgment unrelated to the manipulated cue-target relation suggests strongly that both location-based and frequency-based auditory inhibition of return result primarily because of changes in perceptual sensitivity.     

Facilitative and inhibitory effects of location and frequency cues: evidence of a modulation in perceptual sensitivity.

The possibility that facilitative and inhibitory effects of auditory cues result because of a modulation in perceptual sensitivity was examined. Listeners were presented with a cue followed by a target, with the time period between the two varied at stimulus onset asynchronies (SOAs) of 150, 450, or 750 msec. In two conditions, the cue and target were either the same or different in location or frequency. In both conditions, listeners were required to identify the rise time of the target. Whereas the cue was presented in isolation, the target was presented in a wide-band noise background such that the required discrimination was made relatively difficult. In both conditions, a facilitative effect was apparent at the 150-msec SOA and an inhibitory effect was apparent at the 750-msec SOA for both accuracy and response time measures of performance. That these results were apparent for a judgment unrelated to the manipulated cue-target relation suggests strongly that both location-based and frequency-based auditory inhibition of return result primarily because of changes in perceptual sensitivity.     

Attractors and perceptual field dynamics of homogeneous stimulus areas

Summary The phenomenon of the wandering point on a blank sheet of paper in serial reproductions is the starting point of an investigation of the perceptual field structure of homogeneous stimulus areas; 609 stimulus points distributed regularly in 21 rows and 29 columns on a DIN A4 sheet were presented successively to 10 subjects and had to be reproduced immediately afterwards in order to establish empirical vector fields. These were subjected to vector-analytic procedures. A method for the decomposition of the measured vector fields into partitions from gradient potentials and circulation potentials is demonstrated. The gradient potentials of the empirical vector fields revealed a highly regular structure with four point attractors near the corners of the sheet. A model calculation of the wandering point in this potential landscape showed results comparable to the empirical phenomenon. The results are discussed in favor of Gestalt theory and against direct perception.     

Restricting the field of view: perceptual and performance effects

Visual perception involves both the high acuity of foveal vision and the wide scope of overlapping peripheral information. The role of peripheral vision in competent performance of the adult visuomotor activities of walking, reaching, and forming a cognitive map of a room was examined using goggles which limited the scope of the normal field of view to 9 degrees, 14 degrees, 22 degrees, or 60 degrees. Each restriction of peripheral field information resulted in some perceptual and performance decrements, with the 9 degrees and 14 degrees restriction producing the most disturbance. In addition, bodily discomfort, dizziness, unsteadiness and disorientation, were reported as the subjects moved around with restricted fields of view.     

Memory for spatial location: Cue effects as a function of field rotation

We developed theoretical extensions of Huttenlocher, Hedges, and Duncan's (1991) category-adjustment model of human spatial memory to incorporate the use of fuzzy boundariesand cue-determined prototypes. In two experiments, people reproduced locations of dots in a circle, while the number of external reference cues varied. In Experiment 1, the task field was stable and results were consistent with the use of fixed categories unaffected by number of cues. In Experiment 2, the task field was made dynamic by rotation on most trials, with results evaluated for nonrotation trials. The large cue effects observed for angular bias were consistent with the proposed cue-based fuzzy-boundary model. Large cue effects were also observed for absolute error, consistent with a model in which proximity to cues predicts stability of memory. Results point to the key role of orientation to the task environment in determining whether categorical encoding is based on cues.     

Geometric and perceptual effects of the location of the observer vantage point for linear-perspective images

New geometric analyses are presented of three impressive examples of the effects of location of the vantage point on virtual 3-D spaces conveyed by linear-perspective images. In the 'egocentric-road' effect, the perceived direction of the depicted road is always pointed towards the observer, for any position of the vantage point. It is shown that perspective images of real-observer-aimed roads are characterised by a specific, simple pattern of projected side lines. Given that pattern, the position of the observer, and certain assumptions and perspective arguments, the perceived direction of the virtual road towards the observer can be predicted. In the 'skewed balcony' and the 'collapsing ceiling' effects, the position of the vantage point affects the impression of alignment of the virtual architecture conveyed by large-scale illusionistic paintings and the real architecture surrounding them. It is shown that the dislocation of the vantage point away from the viewing position prescribed by the perspective construction induces a mismatch between the painted vanishing point of elements in the picture and the real vanishing point of corresponding elements of the actual architecture. This mismatch of vanishing points provides visual information that the elements of the two architectures are not mutually parallel.     

Verbal interference in a perceptual comparison task

When Ss had to indicate if the colors of pairs of items from the Stroop test were the same or different, the usual interference effect was completely eliminated. However, when the verbal information consisted of SAME and DIFF rather than color names, interference was reestablished. This indicates that the perceptual comparison task does not eliminate interference simply by rendering Ss insensitive to the meanings of words.