Preattentive processing of audio-visual emotional signals

Previous research has shown that redundant information in faces and voices leads to faster emotional categorization compared to incongruent emotional information even when attending to only one modality. The aim of the present study was to test whether these crossmodal effects are predominantly due to a response conflict rather than interference at earlier, e.g. perceptual processing stages. In Experiment 1, participants had to categorize the valence and rate the intensity of happy, sad, angry and neutral unimodal or bimodal face–voice stimuli. They were asked to rate either the facial or vocal expression and ignore the emotion expressed in the other modality. Participants responded faster and more precisely to emotionally congruent compared to incongruent face–voice pairs in both the Attend Face and in the Attend Voice condition. Moreover, when attending to faces, emotionally congruent bimodal stimuli were more efficiently processed than unimodal visual stimuli. To study the role of a possible response conflict, Experiment 2 used a modified paradigm in which emotional and response conflicts were disentangled. Incongruency effects were significant even in the absence of response conflicts. The results suggest that emotional signals available through different sensory channels are automatically combined prior to response selection.     

Binocular information summation and the serial processing model

An experiment was performed to ascertain whether a particular member of the class of sequential processing models (Estes & Taylor, 1964; Townsend, 1966) should be further developed in terms of the contributions of information from the separate eyes. Using the detection paradigm (Estes & Taylor, 1964), nine Ss were each run 576 trials under each of three viewing conditions: (a) monocular left, (b) monocular right, and (c) binocular, after four days of practice and calibration. The serial processing model was used to make predictions for three possible cases of binocular information summation: (a) complete independence of the monocular channels, (b) partial independence of the monocular channels and (c) complete dependence in the monocular channels. Complete dependence provided the best fit to the data with a possible stress on use of a “best” eye, but a marginal level of significance was obtained between a simple average of monocular performance and binocular performance with transformed scores. Thus, although there seems to be little or no information summation in terms of the present model of multi-symbol perception, follow-up experiments were suggested to further delineate monocular-binocular relationships in the detection paradigm.     

Preattentive control of serial auditory processing in dichotic listening

Dichotic listening performance was examined in an auditory selective attention task where subjects responded to occasional consonant-vowel (CV) or shaped broadband noise-burst (NB) targets in rapid serial auditory presentation (RASP). Trial types were randomized and included monaural CVs and NBs as well as dichotic CV-CV and CV-NB pairings. CVs were spoken by two different voices (male and female), and the two NB stimuli differed in their filter slopes at higher frequencies. The target was designated by stimulus category (/ba/, /da/, /ga/, or NB) and voice (e.g., "female /ba/"). Performance was compared for targets in the left and right ears on monaural and dichotic trials using accuracy and reaction time (RT) measures. Right ear advantages (REAs) were present for CV targets with either CV or NB distractors, but not for monaural CVs. The REA found for monaural NB targets was eliminated by CV distractors, yielding a left ear advantage (LEA) for the distractor effect of CVs on NB targets. The pattern of results suggests initial preprocessing of speech stimuli through phonetic feature analysis, followed by serial attentional processing of the objects in the auditory field. REAs are attributed to a rightward asymmetry in the preattentive control of auditory attention similar to that found in visual search.     

Development of serial processing in reading and rapid naming

Serial rapid automatized naming (RAN) is more strongly related to reading fluency than naming of isolated words, suggesting that the implementation of serial processing may underlie the RAN–reading relationship. In this study, 107 Greek children from Grade 2 and 107 from Grade 6 were tested with discrete and serial naming of digits, objects, and words in 50-item arrays. The correlation between discrete and serial word reading was very high in Grade 2 but only moderate in Grade 6. In confirmatory factor analysis, a reading–naming latent structure fit the Grade 2 data best; in contrast, a serial–discrete structure fit the Grade 6 data. Thus, the superficial longitudinal stability of RAN–reading correlations belies vastly different patterns of interrelations, indicative of changes in the developing cognitive processes underlying both naming and reading. Word fluency tasks in Grade 2 are apparently accomplished largely as a series of isolated individual word naming trials even though multiple individual letters in each word may be processed in parallel. In contrast, specifically serial procedures are applied in Grade 6, presumably via simultaneous processing of multiple individual words at successive levels. It is proposed that this feat requires endogenous control of cognitive cascades.     

Spatial interference between attended items engenders serial visual processing

A pair of experiments investigated the architecture of visual processing, parallel versus serial, across high and low levels of spatial interference in a divided attention task. Subjects made speeded judgments that required them to attend to a pair of color-cued objects among gray filler items, with the spatial proximity between the attended items varied to manipulate the strength of interference between attended items. Systems factorial analysis (Townsend & Nozawa, Journal of Mathematical Psychology 39:321-359, 1995) was used to identify processing architecture. Experiment 1, using moderately dense displays, found evidence of parallel processing whether attended objects were in low or high proximity to one another. Experiment 2, using higher-density displays, found evidence of parallel selection when attended stimuli were widely separated but serial processing when they were in high proximity. Divided visual attention can operate in parallel under conditions of low or moderate spatial interference between selected items, but strong interference engenders serial processing.     

Selective attention and serial processing in briefly presented visual displays

Displays of eight capital letters were presented in a circular arrangement around a central fixation point at tachistoscopic durations. Under different experimental conditions, one or two indicators, presented either 250 msec before, simultaneously with, or after the display, designated the letters that S was to report. The arrangement of conditions permitted inferences as to the order in     

Establishing the loci of serial and parallel effects in syntactic processing

Recent experimental work has demonstrated a robust effect of syntactic context on lexical decision times. Wright and Garrett (1984) report that targets belonging to syntactic categories required by the context produce faster RTs than either ungrammatical or optional continuations of the context string. The present study reports that structurally ambiguous contexts produced faster recognition times for syntactic categories required by only the putative nonpreferred reading of the ambiguities tested. These findings are argued to favor a parallel processing model in which syntactic representations are ranked according to structural criteria and shunted in a serial fashion to subsequent processors.     

Electrophysiological evidence for parallel and serial processing during visual search

Event-related potentials were recorded from young adults during a visual search task in order to evaluate parallel and serial models of visual processing in the context of Treisman's feature integration theory. Parallel and serial search strategies were produced by the use of feature-present and feature-absent targets, respectively. In the feature-absent condition, the slopes of the functions relating reaction time and latency of the P3 component to set size were essentially identical, indicating that the longer reaction times observed for larger set sizes can be accounted for solely by changes in stimulus identification and classification time, rather than changes in post-perceptual processing stages. In addition, the amplitude of the P3 wave on target-present trials in this condition increased with set size and was greater when the preceding trial contained a target, whereas P3 activity was minimal on target-absent trials. These effects are consistent with the serial self-terminating search model and appear to contradict parallel processing accounts of attention-demanding visual search performance, at least for a subset of search paradigms. Differences in ERP scalp distributions further suggested that different physiological processes are utilized for the detection of feature presence and absence.     

Forced serial processing of words and letter strings: A reexamination

Words and nonword strings, three and seven letters long, were displayed serially (i.e., one letter at a time) or simultaneously, with or without a backward mask following display of each letter or string. Recognition of words, and of individual letters within words, was markedly impaired in the masked serial condition relative to the unmasked serial, unmasked simultaneous, and masked simultaneous conditions. Analogous differences were smaller or nonexistent for seven-letter nonwords; however, three-letter nonwords produced relatively “wordlike” data. Implications for the issue of spatially serial vs. parallel processing in word recognition are discussed.     

Evidence for a parallel input serial analysis model of word processing

A parallel input serial analysis (PISA) model of word processing was developed and tested. The goal was to expand on the "critical processing duration" hypothesis of Johnson, Allen, and Strand (1989) so that both single-word and multiple-word presentation, letter detection data could be explained. In Experiments 1-3 four different word frequency categories on a single-presentation, letter detection task were used. These three experiments indicated that there was a curvilinear relationship between word frequency and letter detection reaction time (RT). That is, letter detection RTs for medium-high-frequency words were significantly longer than letter detection RTs for very-high-, low-, and very-low-frequency words. These results support the PISA model rather than the Healy, Oliver, and McNamara (1987) version of the unitization model. In Experiments 4-5 multiple-presentation (i.e., two words), letter detection tasks were used. The PISA model could also account for the results from these two experiments, but the unitization model could not.     

A test of parallel versus serial processing applied to memory retrieval

Townsend has identified necessary and sufficient conditions that reaction time distributions meet if they are produced by two underlying processes that are parallel and within-stage independent. This paper describes an attempt to use one of these conditions to assess the assumption of independent parallel memory retrieval in Anderson's ACT theory. In the experimental test, subjects studied profession-location pairs, with each profession and location included in two pairs. One pair had a high frequency of presentation and the other had low. When cued with a profession (or location), subjects responded with the first of the two studied locations (or professions) that came to mind. The reaction times to these responses were used to test the ACT assumption of independent parallel search. The problems encountered in trying to apply Townsend's abstract test to a concrete situation included the need to consider mixtures and convolutions of distributions and empirical, rather than theoretical, distributions. These difficulties are discussed at length and some formal analyses concerning their effect on the test are given. Despite these problems, we were able to use Townsend's test and the results of the experiment support the within-stage independent parallel assumption of ACT.     

Infants' memory processing of a serial list: list length effects

Six-month-olds, trained with a three-mobile serial list, exhibit a primacy effect 24 h later. In three experiments, we demonstrated that increasing list length impairs their memory for serial order. In all experiments, 6-month-olds were trained with a five-mobile list. In Experiment 1, infants failed to exhibit a primacy effect on a 24-h delayed recognition test, recognizing mobiles from all serial positions. In Experiment 2, infants did exhibit a primacy effect on a reactivation (priming) test, suggesting that they may originally have encoded serial-order information. Experiment 3 confirmed that serial-order information was represented in infants' training memory. After the reactivation treatment, infants were precued with one list member and tested for recognition of another. When precues specified valid order information, infants recognized test mobiles from the later serial positions. The memory dissociation for serial order on delayed recognition and reactivation tests adds to the growing evidence that young infants possess two functionally distinct memory systems.     

Sentence processing: Evidence against the serial,independent stage assumption

The assumption that the processing stages involved in sentence comprehension are serially and independently executed was tested in two separate experiments using two new sentence types. One experiment was a sentence-picture verification task, the other was not. In Experiment I, subjects viewed sentences such as It's false that the dots are red and indicated, by pressing the appropriate response key, which of two colors would make the sentence true. In Experiment II, subjects verified sentences such as It isn't true that the dots aren't red against pictures of colored dots. On the strength of Sternberg's additive factor method, present findings challenge the validity of the serial, independent stage assumption, and results are alternatively discussed in terms of a capacity sharing model.This research was supported by PHS research grant MH 23401 to Sam Glucksberg, principal investigator.     

Evidence from mutual masking for serial processing of tachistoscopic letter patterns.

This experiment deomonstrates serial processing of tachistoscopic patterns when all potential artifacts are eliminated. Two nonsense arrays of six letters were tachistoscopically exposed successively at the same positions. Ss identified more letters from the temporally first string on the left of fixation and more from the second on the right, indicating left-to-right serial processing. Variations among Ss in the location of the crossover in curves indicate individual differences in processing time. Therefore, this study demonstrates definitively that tachistoscopic performance at various positions can reflect a sequential left-to-right processing of information, possibly at different rates.     

Changes in alertness and processing capacity in a serial learning task

Second-to-second changes in processing capacity were examined using a concurrent task paradigm involving serial learning and simple reaction time (RT) in two experiments. Experiment 1 demonstrated the feasibility of combining probe RT with a slow-paced serial learning task including perceptually isolated items. Experiment 2 employed the same concurrent tasks to compare cardiac interbeat interval (IBI, the reciprocal of heart rate) with probe RT. Second-to-second changes during item processing were found consistently for both measures. However, these changes appeared to be more related to observing and response requirements than to the specific cognitive processes required by the tasks. Correctly anticipated items were associated with (l)RT changes, suggesting heightened allocation of capacity, and (2)a cardiac IBI response of episodic cardiac deceleration imposed upon the task-induced cardiac speeding. The probe RT and cardiac IBI measures showed reasonable convergence in assessing the allocation of processing capacity. The concept of the accessibility of allocated capacity was introduced in considering instances of the divergence of probe RT and cardiac IBI.     

From parallel to serial processing: a computational study of visual search

A novel computational model of a preattentive system performing visual search is presented. The model processes displays of lines, reproduced from Wolfe, Friedman-Hill, Stewart, and O'Connell's (1992) and Treisman and Sato's (1990) visual-search experiments. The response times measured in these experiments suggest that some of the displays are searched serially, whereas others are scanned in parallel. Our neural network model operates in two phases. First, the visual displays are compressed via standard methods (principal component analysis), to overcome assumed biological capacity limitations. Second, the compressed representations are further processed to identify a target in the display. The model succeeds in fast detection of targets in experimentally labeled parallel displays, but fails with serial ones. Analysis of the compressed internal representations reveals that compressed parallel displays contain global information that enables instantaneous target detection. However, in representations of serial displays, this global information is obscure, and hence, a target detection system should resort to a serial, attentional scan of local features across the display. Our analysis provides a numerical criterion that is strongly correlated with the experimental response time slopes and enables us to reformulate Duncan and Humphreys's (1989) search surface, using precise quantitative measures. Our findings provide further insight into the important debate concerning the dichotomous versus continuous views of parallel/serial visual search.