Hemispheric differences in processing visual patterns

The dichotomies verbal/visuospatial, serial/parallel and analytic/holistic are reviewed with respect to differences in hemispheric processing. A number of experimental parameters may be varied in such tasks, and together with certain frequently-occurring weaknesses of experimental design may account for the often discrepant results hitherto reported. The above factors are systematically reviewed, and three further experiments are reported which attempt to fill in the missing designs. Further evidence is given in support of the hypothesis that right-hemisphere superiority is most apparent in processes leading to identity matching. It is quantitative rather than qualitative, and may depend upon operations on the entire gestalt, such as holistic matching, mental rotation, reflection, distortion, etc., rather than, e.g., simultaneous (parallel) processing of discretely analysed or isolated features or elements. On the other hand left-hemisphere involvement in visuospatial processing is thought to reflect analysis of the configuration into its separable components; such processing may be either serial or parallel, and may frequently lead to a judgement different.     

Amodal processing of visual speech as revealed by priming

This study investigated the linguistic processing of visual speech (video of a talker's utterance without audio) by determining if such has the capacity to prime subsequently presented word and nonword targets. The priming procedure is well suited for the investigation of whether speech perception is amodal since visual speech primes can be used with targets presented in different modalities. To this end, a series of priming experiments were conducted using several tasks. It was found that visually spoken words (for which overt identification was poor) acted as reliable primes for repeated target words in the naming, written and auditory lexical decision tasks. These visual speech primes did not produce associative or reliable form priming. The lack of form priming suggests that the repetition priming effect was constrained by lexical level processes. That priming found in all tasks is consistent with the view that similar processes operate in both visual and auditory speech processing.     

Sequential effects of phonological priming in visual word recognition

Two masked priming experiments were conducted to examine phonological priming of bisyllabic words in French, and in particular, whether it operates sequentially or in parallel. Bisyllabic target words were primed by pseudowords that shared either the first or the second phonological syllable of the target. Overlap of the first syllable only-not the second-produced facilitation in both the lexical decision and the naming tasks. These findings suggest that, for polysyllabic words, phonological codes are computed sequentially during silent reading and reading aloud.     

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.     

Modality-specificity effects in priming of visual and auditory word-fragment completion

In this study, the researchers examined modality-specificity effects in priming of visual and auditory word-fragment completion by the presentation of visual or auditory primes. In 2 experiments, within-modality priming and cross-modality priming were observed, with greater priming observed in the within-modality conditions. The prime was presented in a word list in Experiment 1 and either presented or inferred in priming sentences in Experiment 2. Inferring a target that was not actually presented in the sentences resulted in priming of fragment completion but not in modality specificity. These results, coupled with comparisons to explicit cued fragment completion, support the interpretation that priming of word-fragment completion is owing to both a perceptual and a nonperceptual component. This latter component may be different than the conceptual processes used for explicit memory, which did show modality specificity for inferred targets.     

Part-whole relationships in the processing of small visual patterns

Subjects seem to react to a word faster than they react to a letter within a word. One interpretation is that words are processed holistically; another is that all visual stimuli are processed in terms of components, but that more stimulus information is available for use when the targets are words than when they are letters within words. The results of three experiments indicate that the word or pattern-level advantage occurs even when the stimulus information in the two situations is equated, but if the perceptual arrays cannot be unitized (e.g., consonant sequences), a pattern-level advantage does not occur. In addition, the experiments provide substantial evidence to indicate that if letter arrays cannot be unitized, then they are processed on a componentby-component basis, rather than holistically. Finally, the appropriate definition ofholistic processing is considered.     

Semantic priming effects on picture and word processing

The effects of semantic priming on picture and word processing were assessed under conditions in which subjects were required simply to identify stimuli (label pictures or read words) as rapidly as possible. Stimuli were presented in pairs (a prime followed by a target), with half of the pairs containing members of the same semantic category and half containing unrelated concepts. Semantic relatedness was found to facilitate the identification of both pictures (Experiment 1) and words (Experiment 2), and obtained interactions of semantic relatedness and stimulus quality in both experiments suggested that semantic priming affects the initial encoding of both types of stimuli. In Experiment 3, subjects received pairs of pictures, pairs of words, and mixed pairs composed of a picture and a word or of a word and a picture. Significant priming effects were obtained on mixed as well as unmixed pairs, supporting the assumption that pictures and words access semantic information from a common semantic store. Of primary interest was the significantly greater priming obtained in picture-picture pairs than in word-word or mixed pairs. This suggests that, in addition to priming that is mediated by the semantic system, priming may occur in picture-picture pairs that results from the overlap in visual features common to the pictorial representations of objects from the same semantic category.     

Examining the visual processing patterns of lonely adults

Prior research has shown that loneliness is associated with hypervigilance to social threats, with eye‐tracking research showing lonely people display a specific attentional bias when viewing social rejection and social exclusion video footage (Bangee, Harris, Bridges, Rotenberg & Qualter, 2014; Qualter, Rotenberg, Barrett et al ., 2013). The current study uses eye‐tracker methodology to examine whether that attentional bias extends to negative emotional faces and negative social non‐rejecting stimuli, or whether it could be explained only as a specific bias to social rejection/exclusion. It is important to establish whether loneliness relates to a specific or general attention bias because it may explain the maintenance of loneliness. Participants (N = 43, F = 35, M age = 20 years and 2 months, SD = 3 months) took part in three tasks, where they viewed different social information: Task 1 – slides displaying four faces each with different emotions (anger, afraid, happy and neutral), Task 2 – slides displaying sixteen faces with varying ratios expressing happiness and anger, and Task 3 – slides displaying four visual scenes (socially rejecting, physically threatening, socially positive, neutral). For all three tasks, eye movements were recorded in real time with an eye‐tracker. Results showed no association between loneliness and viewing patterns of facial expressions, but an association between loneliness and hypervigilant viewing of social rejecting stimuli. The findings indicate that lonely adults do not have a generalised hypervigilance to social threat, but have, instead, a specific attentional bias to rejection information in social contexts. Implications of the findings for interventions are discussed.     

The gravity of unwanted thoughts: Asymmetric priming effects in thought suppression

An unwanted thought appears to be cued easily by reminders in the environment but often the thought itself seems to cue nothing more than the desire to eliminate it from consciousness. This unusual asymmetry in the way unwanted thoughts are linked to other thoughts was the focus of the present research. Participants who were asked to suppress a thought or to concentrate on it completed a task assessing the influence of priming on reaction time (RT) for word/non-word judgments. Results revealed that suppression under cognitive load produced asymmetric priming: Priming with the associate of a suppressed word speeded RT for the suppressed word, but priming with a suppressed word did not speed RT for associated words. These findings suggest that thought suppression induces an unusual form of cognitive accessibility in which movement of activation toward the suppressed thought from associates is facilitated but movement of activation away from the suppressed thought to associates is undermined.     

Semantic priming in visual word recognition: Activation blocking and domains of processing

The fact that letter search on a prime eliminates the typically robust semantic priming effect in lexical decision is often attributed to the “shallowness” of the prime-processing task. In three experiments we investigated this claim by using two different “shallow” prime-processing tasks: letter search and color identification. Consistent with previous reports, lexical decisions to semantically related targets were not facilitated when subjects searched the prime for a probe letter. In contrast, semantic priming was observed following a color discrimination task on the prime. We suggest that a levels-of-processing interpretation is not an adequate framework for understanding these data. Instead, a domain-specific processing account is offered in which explicit processing at the letter level (as in letter search) makes demands on resources (e.g., activation) that drives processing at the semantic level. This competition is resolved by establishing a temporary activation block at the lexical-semantic interface, which results in the elimination or attenuation of semantic priming. In contrast, global judgment of color is viewed as a domain that does not make demands on the resources that drive the visual word recognition machinery. There is therefore no need for an activation block, and semantic priming is not prevented.     

Asymmetric influences of temporally vs. nasally presented masked visual information: evidence for collicular contributions to nonconscious priming effects

It was tested whether the retino-collicular projection allows for the processing of nonconsciously registered visual information in healthy individuals. Masked primes were presented to different visual hemifields. Because the retino-collicular projection is stronger for temporal than for nasal hemifields, priming should be stronger by temporal than by nasal primes. This pattern was tested in two experiments (Experiments 1 and 3). Further, with less peripheral primes, only available to weaker parts of the retino-collicular projection, hemifield asymmetries of priming vanished (Experiment 2). In conclusion, the study offers first evidence for collicular contributions to nonconscious priming effects by visual information in healthy individuals.     

Attentional sensitization of unconscious visual processing: Top-down influences on masked priming

Classical theories of automaticity assume that automatic processes elicited by unconscious stimuli are autonomous and independent of higher-level cognitive influences. In contrast to these classical conceptions, we argue that automatic processing depends on attentional amplification of task-congruent processing pathways and propose an attentional sensitization model of unconscious visual processing: According to this model, unconscious visual processing is automatic in the sense that it is initiated without deliberate intention. However, unconscious visual processing is susceptible to attentional top-down control and is only elicited if the cognitive system is configured accordingly. In this article, we describe our attentional sensitization model and review recent evidence demonstrating attentional influences on subliminal priming, a prototypical example of an automatic process. We show that subliminal priming (a) depends on attentional resources, (b) is susceptible to stimulus expectations, (c) is influenced by action intentions, and (d) is modulated by task sets. These data suggest that attention enhances or attenuates unconscious visual processes in congruency with attentional task representations similar to conscious perception. We argue that seemingly paradoxical, hitherto unexplained findings regarding the automaticity of the underlying processes in many cognitive domains can be easily accommodated by our attentional sensitization model. We conclude this review with a discussion of future research questions regar-ding the nature of attentional control of unconscious visual processing.     

Memory effects in visual spatial information processing

Eight, ten and twelve year old children were tested on a novel procedure involving the successive presentation of the standard and comparison stimuli. Two hypotheses were evaluated, one dealing with memory effects, and the other with children's pre-testing of choice responses in spatial information processing. It was found, in general, for both spatial perception and coordination of perspectives tasks, that there was no short memory decay for spatial information, but that opportunities to pre-test choice responses improved performance. It was inferred from these data that the performance superiority under simultaneous than successive conditions is attributable to opportunities to pre-test responses and not to memory effects, as opposed to successive conditions is attributable to opportunities to pre-test responses and not to memory effects.     

Serial processing of visual spatial patterns in a search paradigm

Previous experiments in this laboratory employing a search paradigm have found highly significant differences in the detectability of a briefly exposed target pattern as a function of the spatial location of the target when it is presented simultaneously with a number of discriminably different nontarget patterns. These detectability differences, at loci equidistant from the fovea, could not be accounted for by any known variation in retinal spatial resolution or by differential lateral masking effects of the target by nearby nontarget patterns. These observations led to the hypothesis that the target in these experiments was detected by a serial mechanism which "scanned" a persisting but rapidly degrading neural representation of the visual scene with increasing detection failures the later in time the scan processed the location occupied by the target. If this hypothesis is correct, then target detectability should vary inversely with the number of stimuli which must be examined. The present experiment confirmed this expectation. A mathematical model of such a serial scanning process also predicts other, less obvious, effects on target detectability which were observed when the number of nontarget patterns was changed.     

An event-related brain potential analysis of visual word priming effects

Two experiments are reported that provide evidence on task-induced effects during visual lexical processing in a prime-target semantic priming paradigm. The research focuses on target expectancy effects by manipulating the proportion of semantically related and unrelated word pairs. In Experiment 1, a lexical decision task was used and reaction times (RTs) and event-related brain potentials (ERPs) were obtained. In Experiment 2, subjects silently read the stimuli, without any additional task demands, and ERPs were recorded. The RT and ERP results of Experiment 1 demonstrate that an expectancy mechanism contributed to the priming effect when a high proportion of related word pairs was presented. The ERP results of Experiment 2 show that in the absence of extraneous task requirements, an expectancy mechanism is not active. However, a standard ERP semantic priming effect was obtained in Experiment 2. The combined results show that priming effects due to relatedness proportion are induced by task demands and are not a standard aspect of online lexical processing.     

Visual priming effects as a measure of short-term visual memory

On each trial, subjects classified one of four letters as belonging to one of two categories. Visual priming occurs when the classification response is faster to a stimulus visually identical to a previous stimulus than to one identical only in name. Earlier experiments found no visual priming effects between stimuli separated by a stimulus of the same task but from the opposite classification category. Two of the five conditions in the present experiment varied the stimulus-response (S-R) contingencies in such a way that the penultimate but not the immediately preceding trial had the same contingencies. Only these two conditions gave evidence of the above type of visual priming. Visual priming was found, however, in almost all conditions when the intervening stimulus was from the same task and the same classification category. It is argued that a similarity of S-R contingency, and not simply stimulus similarity, is an important component of the visual priming effect.     

Auditory accessory effects on visual processing

A series of experiments on intersensory facilitation demonstrates that non-informative sound of low to moderate intensity (30/80 dB) facilitates the reaction to a visual stimulus. By manipulating the preprocessing and perceptual stages of the visual signals, it appears that auditory intensity reduces choice reaction time independently from the positive influence of the intensity and duration of the visual imperative signal, but interacts with the effect of stimulus degradation. Degraded stimuli take more profit of the sound than intact stimuli. Besides a short-term activation effect, originated by accessories of the auditory modality, on the motor adjustment stage (cf. Sanders 1983), the results suggest that the accessory influences the stage of feature extraction.     

The effects of emotion priming on visual search in socially anxious adults

This study examined the effects of emotion priming on visual search in participants characterised for different levels of social anxiety. Participants were primed with five facial emotions (angry, fear, happy, neutral, and surprised) and one scrambled face immediately prior to visual search trials involving finding a slanted coloured line amongst distractors, as reaction times and accuracy to target detection were recorded. Results suggest that for individuals low in social anxiety, being primed with an angry, surprised, or fearful face facilitated visual search compared to being primed with scrambled, neutral or happy faces. However, these same emotions degraded visual search in participants with high levels of social anxiety. This study expands on previous research on the impact of emotion on attention, finding that amongst socially anxious individuals, the effects of priming with threat extend beyond initial attention capture or disengagement, degrading later visual search.     

Morphological processing during visual word recognition in developing readers: evidence from masked priming

Masked priming studies with adult readers have provided evidence for a form-based morpho-orthographic segmentation mechanism that "blindly" decomposes any word with the appearance of morphological complexity. The present studies investigated whether evidence for structural morphological decomposition can be obtained with developing readers. We used a masked primed lexical decision design first adopted by Rastle, Davis, and New (2004), comparing truly suffixed (golden-GOLD) and pseudosuffixed (mother-MOTH) prime-target pairs with nonsuffixed controls (spinach-SPIN). Experiment 1 tested adult readers, showing that priming from both pseudo- and truly suffixed primes could be obtained using our own set of high-frequency word materials. Experiment 2 assessed a group of Year 3 and Year 5 children, but priming only occurred when prime and target shared a true morphological relationship, and not when the relationship was pseudomorphological. This pattern of results indicates that morpho-orthographic decomposition mechanisms do not become automatized until a relatively late stage in reading development.