Channel capacity and processing of modality specific information

The synthesis model, designed to explain effects of modality specific information on retention, is presented and tested. The model encompasses qualitative and quantitative components. The qualitative characteristics reflect the physiological properties of the auditory and visual channels. Three parameters are assumed to affect the quantitative efficiency of the channels. Each channel is assumed to have a certain capacity, and processing of information in the channels is determined by situational demands. Furthermore, processing in a channel is regarded as superficial. Increased allocation of processing to the superficial level was manipulated by the use of modality specific distractors and conditions of ‘supracapacity load’. Transformation of information from the visual to the auditory channel was controlled by the use of one mixed-mode and one single-mode experiment. Thirty subjects participated in the mixed-mode experiment and 60 in the single-mode experiment. Both experiments employed an identical distraction task, intervening presentation and free recall of the to-be-remembered items. The results confirmed the predictions of (a) modality specific distraction, (b) supracapacity performance decrement, (c) a larger distraction effect for the auditory channel and (d) transformation effects in the single-mode experiment.     

Locus and persistence of capacity limitations in visual information processing

Although there is considerable evidence that stimuli such as digits and letters are extensively processed in parallel and without capacity limitations, recent data suggest that only the features of stimuli are processed in parallel. In an attempt to reconcile this discrepancy, we used the simultaneous/successive detection paradigm with stimuli from experiments indicating parallel processing and with stimuli from experiments indicating that only features can be processed in parallel. In Experiment 1, large differences between simultaneous and successive presentations were obtained with an R target among P and Q distractors and among P and B distractors, but not with digit targets among letter distractors. As predicted by the feature integration theory of attention, false-alarm rates in the simultaneous condition were much higher than in the successive condition with the R/PQ stimuli. In Experiment 2, the possibility that attention is required for any difficult discrimination was ruled out as an explanation of the discrepancy between the digit/letter results and the R/PQ and R/PB results. Experiment 3A replicated the R/PQ and R/PB results of Experiment 1, and Experiment 3B extended these findings to a new set of stimuli. In Experiment 4, we found that large amounts of consistent practice did not generally eliminate capacity limitations. From this series of experiments we strongly conclude that the notion of capacity-free letter perception has limited generality.     

Refractoriness in information processing

Two experiments on refractoriness were carried out in which the warning, first and second signals, S₀, S₁ and S₂ respectively, were all single-valued, and the distributions of random intervals between S₀ and S₁, and S₁ and S ₂ were the same. In the first experiment the intervals in a trial were statistically independent: the null hypothesis, that the latencies of the two responses would be similar, was rejected, but the results were also found to agree with no existing alternative hypothesis. In the second experiment the intervals in a trial were conditionally related and the second response was found to be faster than in the first experiment. This is discussed in the context of the issue of serial or parallel processing of information.     

Chromatic information processing

The investigation of visual processing mediated solely by chromatic information requires conditions preventing a subject's use of the luminance differences normally accompanying a chromatic change. In Experiment 1, which involved a discriminative reaction time (RT) task, chromatic and white stimuli of the same luminance were presented on a dimmer achromatic background. Subjects were instructed to respond only to the chromatic stimuli. RT was slowest at 570 nm and somewhat faster to short wavelengths than to long wavelengths. In Experiment 2, which compared two discriminative RT tasks, RT was faster when subjects responded to color than when they responded to white. Experiments 3 and 4 demonstrated that a brighter white surround decreased the perceived brightness of chromatic stimuli as well as their perceptual similarity to white, but did not affect RT. The results are discussed in terms of the response strength of the chromatic processing channel.     

Selective information processing

Past studies have shown that in certain tasks, subjects are not able to selectively attend to specific areas of a visual display even if instructed to do so. Yet, a more recent study (Graves, 1976) has used the concept of selective attention to explain the difference between the number of items processed in forced choice detection tasks and the number processed in full report tasks. Graves proposed that only identification processing is necessary in the detection task, while both identification and position processing are required in the full report task. A problem with Graves’ task is that it requires memory searching after stimulus presentation, probably reducing the predicted number of items processed. The experiment reported here utilized partially filled arrays and required responses based upon only positional processing, or only identification processing, or both types of processing. In direct contradiction to Graves’ conclusions, the results showed that although subjects could inhibit identification processing while engaged in positional processing, the reverse was not true. In addition, positional processing was shown to be faster than identification processing.     

Sex differences in information processing

Sex differences in cognitive activity were investigated. Using a list containing words with masculine, feminine, and neutral connotations, Experiment 1 revealed that masculine words were better recalled by male college students (n=16) while feminine words were better recalled by female college students (n=16). This difference was reduced on a recognition test. Experiment 2 demonstrated that the phenomenon was not due to a difference in the way males (n=20) and females (n=20) interpreted the meaning of the words. Finally, in Experiment 3, the memorial selectivity was shown to exist in the same manner for White middle-class elementary school (n=32) and high school (n=32) students. Learning and repression interpretations of the effect were proposed. Some practical implications of the data were suggested.These investigations were supported by a seed grant to the first author. This grant was jointly funded by Southern Methodist University and the National Science Foundation's Institutional Grants for Science Program (GU-3752). The authors would like to express their appreciation to the pupils and teachers on Fain Elementary School and Rider High School, both in Wichita Falls, Texas.     

Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach

A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.     

Stereotype strength and attentional bias: Preference for confirming versus disconfirming information depends on processing capacity

In two experiments, we investigated the relationships among stereotype strength, processing capacity, and the allocation of attention to stereotype-consistent versus stereotype-inconsistent information describing a target person. The results of both experiments showed that, with full capacity, greater stereotype strength was associated with increased attention toward stereotype-consistent versus stereotype-inconsistent information. However, when capacity was diminished, greater stereotype strength was associated with increased attention toward inconsistent versus consistent information. Thus, strong stereotypes may act as self-confirming filters when processing capacity is plentiful, but as efficient information gathering devices that maximize the acquisition of novel (disconfirming) information when capacity is depleted. Implications for models of stereotyping and stereotype change are discussed.     

Structural information processing in peripheral vision

Structural visual information processing was investigated in peripheral vision. Perceptual completion, as observed at the blind spot, occurred across a vertical blank stripe in a test pattern, presented in the peripheral visual field. That is, a shape, organized by structural processing, was perceived under critical visual conditions when it was presented in peripheral vision. The results indicate that structural processing, as indicated by perceptual completion, occurs in the peripheral visual information handling process. The results suggest that structural processing of shape information is built into the peripheral visual system and reduces the information load on the higher visual processes under conditions in which visual information is not adequate.     

Configurational effects in visual information processing

These experiments show that the perceptual organization of a multielement display affects both the speed and accuracy with which a target letter in it is detected. The first two experiments show that a target is detected more poorly if it is arranged in good form (a perceptual Gestalt) with noise elements than if it is not. This effect is not confounded with target-noise proximity or display size, and it holds for stimuli terminated by the subject’s response as well as for stimuli of very brief duration. Increasing the number of noise elements can actually improve performance if the added noise elements increase the degree to which the noise elements form perceptual groups separately from the target. A third experiment tries out a new method for scaling the perceptual structure of an array, and it shows that the main features of the first two experiments can be predicted from the scaled perceptual structure of the arrays they used.     

Modelling age-related changes in information processing

Researchers in cognitive ageing seldom take advantage of explicit quantitative models of information processing to account for age differences in cognition. Where quantitative models have been used, these models typically remain silent about the details of information processing. The lack of explicit cognitive models has consequences for the interpretation of a number of empirical results. Using a specific class of models called random walk models, I review evidence showing that the empirical relations taken as support for global age-related changes are consistent with a number of possible age effects on information processing. In addition, I demonstrate that these models can be used to account for age differences within the context of individual experiments and such modelling has important implications for the interpretation of age differences in performance.     

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.     

Lateral masking in visual information processing

When unrelated letter strings are presented tachistoscopically, the end letters are reported more often than their neighbors; and when spaces are inserted into strings, performance on certain adjacent letters is superior to performance on those letters when no spaces were present. An experiment was conducted to determine the nature of those spacing effects. Letter strings were presented at a variety of retinal locations, and spaces were inserted into different positions in the instructed left-right processing order. The space effect was unrelated to processing order, but it was dependent on retinal location. To account for the various asymmetries, it was necessary to postulate that letters tend to interact with adjacent lettersand that the interaction was not spatially symmetric. Furthermore, it was found that spaces had greater effects on “right-hand” letters than on symmetric letters. It was therefore concluded that letters interact at the feature level.     

Continuous information processing in conceptual identifications

Summary This investigation was aimed at the analysis of processes of the conceptual object identification. Three experiments were performed which utilized a response preparation paradigm developed by Miller (1982). The results confirm the psychological validity of a distinction between sensorily and categorially represented concepts proposed formerly by the authors. The process of identification of objects as belonging to sensory concepts was analysed in more detail. The experimental results suggest that it may be a sequential feature matching process which is characterized by continuous information processing. Early in the process the figurative features allowing an identification of an object as belonging to a more general sensory concept are processed. In following processing stages this first conceptual identification is more and more specified by an additional checking of more detailed figurative features. More importantly, the results indicate that the information about the general conceptual identity of an object is not only available early in the identification process but can also be used for the preparation of following processes or processing stages even before the object is fully identified. Possible influences of the early information on the control of the conceptual identification itself and on the selection and control of motor behavior are discussed.We wish to thank the following psychology students at the Humboldt University in Berlin for their help in performing the experiments: Kathrin Hänel, Erika Küchler and Christina Matthé. Furthermore, we wish to thank the two anaonymous reviewers and Johannes Engelkamp for their helpful comments on a first draft of our paper     

Visual information processing in hemispatial neglect

Hemispatial neglect is a complex neuropsychological disorder characterized by a severe attentional deficit that produces a lack of awareness for information appearing in contralesional hemispace. Despite this lack of phenomenal awareness, recent studies suggest that a great deal of visual information processing does occur and can influence the performance of patients in certain tasks. The current review will present this evidence and suggest a new theoretical framework that may help to direct future research into uncovering the underlying mechanism(s).     

Neuromuscular circuits in affect-laden information processing

Substantial evidence has accrued indicating the involvement of neuromuscular circuits in covert information processing. The physiological systems impartingemotional tone to covert processing, however, are less well understood. Reviewed here are findings from a variety of methodologies which suggest that somatic patterns, particularly in the face, reflect moment by moment emotional reactions. These findings imply neuromuscular involvement in affect-laden information processing; less conclusive, though suggestive, are data indicating that the proprioceptive feedback from these phasic and specific patterns of response are integrated cortically and influence covert processing and overt responding.     

Capacity limitations in human information processing

The nature of processing demands during a letter-match task was investigated in an extension of the Posner and Boies (1971) paradigm. In Experiment I, a visual probe was employed in addition to an auditory probe in two different experimental conditions. The shape of the auditory probe reaction time (RT) function was similar to that found by Posner and Boies. However, in contrast to their findings, RT was greatly increased shortly after presentation of the first letter for the visual probe function. It was concluded that perceptual as well as postperceptual limitations on processing capacity exist. A second experiment provided further support for this hypothesis.