Preattentive Processing Research Articles

Visual search.

Visual search is the act of looking for a predefined target among other objects. This task has been widely used as an experimental paradigm to study visual attention, and because of its influence has also become a subject of research itself. When used as a paradigm, visual search studies address questions including the nature, function, and limits of preattentive processing and focused attention. As a subject of research, visual search studies address the role of memory in search, the procedures involved in search, and factors that affect search performance. In this article, we review major theories of visual search, the ways in which preattentive information is used to guide attentional allocation, the role of memory, and the processes and decisions involved in its successful completion. We conclude by summarizing the current state of knowledge about visual search and highlight some unresolved issues. WIREs Cogn Sci 2013, 4:415-429. doi: 10.1002/wcs.1235 The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

Brain correlates of automatic visual change detection

A number of studies support the presence of visual automatic detection of change, but little is known about the brain generators involved in such processing and about the modulation of brain activity according to the salience of the stimulus. The study presented here was designed to locate the brain activity elicited by unattended visual deviant and novel stimuli using fMRI. Seventeen adult participants were presented with a passive visual oddball sequence while performing a concurrent visual task. Variations in BOLD signal were observed in the modality-specific sensory cortex, but also in non-specific areas involved in preattentional processing of changing events. A degree-of-deviance effect was observed, since novel stimuli elicited more activity in the sensory occipital regions and at the medial frontal site than small changes. These findings could be compared to those obtained in the auditory modality and might suggest a "general" change detection process operating in several sensory modalities.

Sleep Extension Normalizes ERP of Waking Auditory Sensory Gating in Healthy Habitually Short Sleeping Individuals

Chronic sleep loss has been associated with increased daytime sleepiness, as well as impairments in memory and attentional processes. In the present study, we evaluated the neuronal changes of a pre-attentive process of wake auditory sensory gating, measured by brain event-related potential (ERP) – P50 in eight normal sleepers (NS) (habitual total sleep time (TST) 7 h 32 m) vs. eight chronic short sleeping individuals (SS) (habitual TST ≤6 h). To evaluate the effect of sleep extension on sensory gating, the extended sleep condition was performed in chronic short sleeping individuals. Thus, one week of time in bed (6 h 11 m) corresponding to habitual short sleep (hSS), and one week of extended time (∼ 8 h 25 m) in bed corresponding to extended sleep (eSS), were counterbalanced in the SS group. The gating ERP assessment was performed on the last day after each sleep condition week (normal sleep and habitual short and extended sleep), and was separated by one week with habitual total sleep time and monitored by a sleep diary. We found that amplitude of gating was lower in SS group compared to that in NS group (0.3 µV vs. 1.2 µV, at Cz electrode respectively). The results of the group × laterality interaction showed that the reduction of gating amplitude in the SS group was due to lower amplitude over the left hemisphere and central-midline sites relative to that in the NS group. After sleep extension the amplitude of gating increased in chronic short sleeping individuals relative to their habitual short sleep condition. The sleep condition × frontality interaction analysis confirmed that sleep extension significantly increased the amplitude of gating over frontal and central brain areas compared to parietal brain areas.

Response inhibition, preattentive processing, and sex difference in young children

Response inhibition and preattentive processing are two important cognitive abilities for child development, and the current study adopted both behavioral and electrophysiological protocols to examine whether young children's response inhibition correlated with their preattentive processing. A Go/Nogo task was used to explore young children's response inhibition performances and an Oddball task with event-related potential recordings was used to measure their preattentive processing. The behavioral results showed that girls committed significantly fewer commission error rates, which showed that girls had stronger inhibition control abilities than boys. Girls also achieved higher d' scores in the Go/Nogo task, which indicated that they were more sensitive to the stimulus signals than boys. Although the electrophysiological results of preattentive processing did not show any sex differences, the correlation patterns between children's response inhibition and preattentive processing were different between these two groups: the neural response speed of preattentive processing (mismatch negativity peak latency) negatively correlated with girls' commission error rates and positively correlated with boys' correct hit rates. The current findings supported that the preattentive processing correlated with human inhibition control performances, and further showed that girls' better inhibition responses might be because of the influence of their preattentive processing.

Gender Differences in Preattentive Processing of Facial Expressions: An ERP Study

To investigate gender differences in pre-attentive processing of facial expressions we recorded the expression mismatch negativity (EMMN) in the deviant-standard-reverse oddball paradigm. For female participants, sad faces elicited larger EMMN than happy faces, but this difference disappeared in the left hemisphere. For male participants, EMMN was not modulated by facial expressions, regardless of in the left or right hemispheres. While the source analysis indicated that for both genders prefrontal activations were observed for sad EMMN, more sources were involved for male than female participants. For happy EMMN, the current sources were located in the occipital lobe and parietal lobe for females and the temporal lobe and the frontal lobe for males. The present findings emphasized the importance of considering gender as a factor in the study of the pre-attentive processing of facial expressions.

Pre-attentive and attentive vision module

This paper introduces a new vision module, called PAAV, developed for the cognitive architecture ACT-R. Unlike ACT-R’s default vision module that was originally developed for top-down perception only, PAAV was designed to model a wide range of tasks, such as visual search and scene viewing, where pre-attentive bottom-up processes are essential for the validity of a model. PAAV builds on attentive components of the default vision module and incorporates greater support for modeling pre-attentive components of human vision. The module design incorporates the best practices from existing models of vision. The validity of the module was tested on four different tasks.

Robust Pre-Attentive Attention Direction Using Chaos Theory for Video Surveillance

Attention direction for active vision systems has been of substantial interest in the image processing and computer vision communities for video surveillance. Biological vision systems have been shown to possess a hierarchical structure where a pre-attentive processing function directs the visual attention to regions of interest which are then possibly further processed by higher-level vision functions. Biological neural systems are also highly responsive to signals which appear to be chaotic in nature. In this paper we explore applying measures from chaos theory and fractal analysis to provide a robust pre-attentive processing engine for vision. The approach is applied to two standard data sets related to video surveillance for detecting bags left suspiciously in public places. Results compare quite favorably in terms of probability of detection versus false detection rate shown through Receiver Operating Characteristic (ROC) curves against two traditional methods for low-level change detection, namely Mutual Information, Sum of Absolute Differences, and Gaussian Mixture Models.

Does valence in the visual domain influence the spatial attention after auditory deviants? Exploratory data

The auditory mismatch responses are elicited in absence of directed attention but are thought to reflect attention modulating effects. Little is known however, if the deviants in a stream of standards are specifically directing attention across modalities and how they interact with other attention directing signals such as emotions. We applied the well-established paradigm of left- or right-lateralized deviant syllables within a dichotic listening design. In a simple target detection paradigm with lateralized visual stimuli, we hypothesized that responses to visual stimuli would be speeded after ignored auditory deviants on the same side. Moreover, stimuli with negative valence in the visual domain could be expected to reduce this effect due to attention capture for this emotion, resulting in speeded responses to visual stimuli even when attention was directed to the opposite side by the auditory deviant beforehand. Reaction times of 17 subjects confirmed the speeding of responses after deviant events. However, reduced facilitation was observed for positive targets at the left after incongruent deviants, i.e., at the right ear. In particular, significant interactions of valence and visual field and of valence and spatial congruency emerged. Pre-attentive auditory processing may modulate attention in a spatially selective way. However, negative valence processing in the right hemisphere may override this effect. Resource allocation such as spatial attention is regulated dynamically by multimodal and emotion information processing.

The Cortical Evoked Response Elicited by Nine Plosives in Normal Hearing Listeners

Background and ObjectivesP1-N1-P2 complex reflecting pre-attentive processing of sound presents several temporally overlapping and spatially distributed neural sources in or near primary auditory cortex. This study investigated cortical evoked responses to the P1-N1-P2 complex to determine the perceptual contributions of the acoustic features.Subjects and MethodsEleven young native-speaking Korean adults with normal hearing participated. The stimuli were three bilabial, three alveolar, and three velar syllables, and each place of articulation had one lax, one tense, and one aspirate syllable as the manner of articulation.ResultsThe results indicate the cortical responses to the velar syllables significantly differed from the bilabial and alveolar groups at the P1-N1 and N1-P2 interamplitude. However, there is no significant difference in the cortical responses between Korean lax and tense syllables, which is significant for English phonology in terms of voice onset time. Further, the cortical responses to aspirate syllables significantly differed from two other groups in the interamplitude, demonstrating that the /tha/ syllable had the largest response at N1-P2 interamplitude.ConclusionsDifferent speech sounds evoked different P1-N1-P2 patterns in the place and the manner of articulation in terms of interamplitude, but not of the latency and interlatency although further studies should be followed.

Relationship between auditory processing and affective prosody in schizophrenia

Patients with schizophrenia have well-established deficits in their ability to identify emotion from facial expression and tone of voice. In the visual modality, there is strong evidence that basic processing deficits contribute to impaired facial affect recognition in schizophrenia. However, few studies have examined the auditory modality for mechanisms underlying affective prosody identification. In this study, we explored links between different stages of auditory processing, using event-related potentials (ERPs), and affective prosody detection in schizophrenia. Thirty-six schizophrenia patients and 18 healthy control subjects received tasks of affective prosody, facial emotion identification, and tone matching, as well as two auditory oddball paradigms, one passive for mismatch negativity (MMN) and one active for P300. Patients had significantly reduced MMN and P300 amplitudes, impaired auditory and visual emotion recognition, and poorer tone matching performance, relative to healthy controls. Correlations between ERP and behavioral measures within the patient group revealed significant associations between affective prosody recognition and both MMN and P300 amplitudes. These relationships were modality specific, as MMN and P300 did not correlate with facial emotion recognition. The two ERP waves accounted for 49% of the variance in affective prosody in a regression analysis. Our results support previous suggestions of a relationship between basic auditory processing abnormalities and affective prosody dysfunction in schizophrenia, and indicate that both relatively automatic pre-attentive processes (MMN) and later attention-dependent processes (P300) are involved with accurate auditory emotion identification. These findings provide support for bottom-up (e.g., perceptually based) cognitive remediation approaches.

Twelve Months of Active Musical Training in 8- to 10-Year-Old Children Enhances the Preattentive Processing of Syllabic Duration and Voice Onset Time

Musical training has been shown to positively influence linguistic abilities. To follow the developmental dynamics of this transfer effect at the preattentive level, we conducted a longitudinal study over 2 school years with nonmusician children randomly assigned to music or to painting training. We recorded the mismatch negativity (MMN), a cortical correlate of preattentive mismatch detection, to syllables that differed in vowel frequency, vowel duration, and voice onset time (VOT), using a test-training-retest procedure and 3 times of testing: before training, after 6 months and after 12 months of training. While no between-group differences were found before training, enhanced preattentive processing of syllabic duration and VOT, as reflected by greater MMN amplitude, but not of frequency, was found after 12 months of training in the music group only. These results demonstrate neuroplasticity in the child brain and suggest that active musical training rather than innate predispositions for music yielded the improvements in musically trained children. These results also highlight the influence of musical training for duration perception in speech and for the development of phonological representations in normally developing children. They support the importance of music-based training programs for children's education and open new remediation strategies for children with language-based learning impairments.

Influence of Music Training on Pre-Attentive Auditory-Neural Processing Across the Lifespan

Music training has been shown to enhance auditory sensory-memory for acoustic features and augment sensitivity to acoustic changes in spectrally rich stimuli for children and young adults. Less is ...

Pre-attentive modulation of brain responses to tones in coloured-hearing synesthetes.

BackgroundColoured-hearing (CH) synesthesia is a perceptual phenomenon in which an acoustic stimulus (the inducer) initiates a concurrent colour perception (the concurrent). Individuals with CH synesthesia "see" colours when hearing tones, words, or music; this specific phenomenon suggesting a close relationship between auditory and visual representations. To date, it is still unknown whether the perception of colours is associated with a modulation of brain functions in the inducing brain area, namely in the auditory-related cortex and associated brain areas. In addition, there is an on-going debate as to whether attention to the inducer is necessarily required for eliciting a visual concurrent, or whether the latter can emerge in a pre-attentive fashion.ResultsBy using the EEG technique in the context of a pre-attentive mismatch negativity (MMN) paradigm, we show that the binding of tones and colours in CH synesthetes is associated with increased MMN amplitudes in response to deviant tones supposed to induce novel concurrent colour perceptions. Most notably, the increased MMN amplitudes we revealed in the CH synesthetes were associated with stronger intracerebral current densities originating from the auditory cortex, parietal cortex, and ventral visual areas.ConclusionsThe automatic binding of tones and colours in CH synesthetes is accompanied by an early pre-attentive process recruiting the auditory cortex, inferior and superior parietal lobules, as well as ventral occipital areas.

Visual search for expressions and anti-expressions

We used visual search to explore whether the preattentive mechanisms that enable rapid detection of facial expressions are driven by visual information from the displacement of features in expressions, or other factors such as affect. We measured search slopes for luminance and contrast equated images of facial expressions and anti-expressions of six emotions (anger, fear, disgust, surprise, happiness, and sadness). Anti-expressions have an equivalent magnitude of facial feature displacements to their corresponding expressions, but different affective content. There was a strong correlation between these search slopes and the magnitude of feature displacements in expressions and anti-expressions, indicating feature displacement had an effect on search performance. There were significant differences between search slopes for expressions and anti-expressions of happiness, sadness, anger, and surprise, which could not be explained in terms of feature differences, suggesting preattentive mechanisms were sensitive to other factors. A categorization task confirmed that the affective content of expressions and anti-expressions of each of these emotions were different, suggesting signals of affect might well have been influencing attention and search performance. Our results support a picture in which preattentive mechanisms may be driven by factors at a number of levels, including affect and the magnitude of feature displacement. We note that indirect effects of feature displacement, such as changes in local contrast, may well affect preattentive processing. These are most likely to be nonlinearly related to feature displacement and are, we argue, an important consideration for any study using images of expression to explore how affect guides attention. We also note that indirect effects of feature displacement (for example, changes in local contrast) may well affect preattentive processing. We argue that such effects are an important consideration for any study using images of expression to explore how affect guides attention.

Cognitive Training for Psychiatric Disorders

Psychiatric disorders are associated with impairments in neural system activity and connectivity across distributed networks that underlie cognition and social–emotional processes. Increasing evidence indicates that these neural system dysfunctions are not immutably fixed, but instead may be amenable to well-designed cognitive training interventions that target restoration of neural system operations (Browning et al, 2012; Klingberg et al, 2005; Subramaniam et al, 2012). An explicitly ‘systems neuroplasticity'-based approach to cognitive training is founded on the premise that during successful skill learning, disproportionately larger and better-coordinated neuronal populations represent the salient inputs and action outputs of the trained skill, resulting in an increased feed-forward signal strength from sensory regions as well as greater task-relevant feedback-inhibitory control from the prefrontal cortex to enhance representations of relevant stimuli, and to enable more efficient and accurate associative memory processes (Vinogradov et al, 2012). Effective cognitive training must target the underlying neural impairments associated with a specific pathophysiology. For children with ADD, for example, Klingberg et al 2005 found that computerized visual working memory (WM) exercises drove improvements in non-trained visuospatial and executive tasks, indicating generalization of training. This group also found that WM training improved WM capacity, which was correlated with neural changes in D1 receptor density, indicating increased dopaminergic release during training (Klingberg, 2010; McNab et al, 2009). Browning et al (2012) investigated attentional bias modification (ABM) training in remitted patients with depression, and found that ABM reduced residual depressive symptoms and normalized the cortisol awakening response, suggesting that it may be a ‘cognitive vaccine' that reduces the neurobehavioral risk for future depression episodes. Our group recently performed a double-blind randomized controlled trial of a set of computerized exercises that focused on early auditory and visual processing, WM and basic social cognition (vs computer games control condition) in individuals with schizophrenia. Our rationale was that schizophrenia is characterized by deficits in both early pre-attentive perceptual processes as well as higher-order attention and WM operations (Vinogradov et al, 2012). We found that the schizophrenia participants who received the targeted training showed behavioral improvements on (untrained) neuropsychological measures of verbal memory and on reality-monitoring tasks, thus indicating generalization of training effects. Further, after the intervention, neural activation patterns during reality monitoring, which were abnormal in these patients at baseline, began to resemble the patterns observed in healthy participants (Figures 1a and c), and predicted better social functioning 6 months later (Subramaniam et al, 2012). Figure 1 Whole-brain fMRI analysis of reality-monitoring activity reveals signal increase within: (a) the medial prefrontal cortex (mPFC) in 15 healthy comparison (HC) subjects, (b) the posterior cingulate cortex, rather than the mPFC, in patients with schizophrenia ... Together, these emerging data suggest that people with a range of neuropsychiatric illnesses can benefit from targeted cognitive training; that this type of training can ‘restore' aspects of behavior and neural system functioning; and that this training can be generalized to enduring improvements in real-world functioning (Browning et al, 2012; Klingberg et al, 2005; Subramaniam et al, 2012). Future studies must examine the specific intervention methods that promote maximal cognitive and neural system ‘restoration' in the neuropsychiatrically impaired brain—likely by combining targeted cognitive training approaches with cognitive enhancing medications and neuromodulation techniques such as transcranial direct current stimulation.

Impaired pre-attentive change detection in major depressive disorder patients revealed by auditory mismatch negativity

Patients with major depressive disorder (MDD) show deficits in cognitive functions. However, the neural mechanisms underlying the pre-attentive information processing in MDD patients are poorly understood. The present study investigated whether MDD patients have impairments in pre-attentive information processing indexed by auditory mismatch negativity (MMN). The deviant-standard reverse oddball paradigm was used to obtain the memory-comparison-based duration auditory MMN in 24 MDD patients and 24 healthy control subjects. Over the frontal–central area, MDD patients exhibited decreased MMN amplitudes only for the increment condition (150-ms MMN), whereas the temporal MMN did not differ between MDD patients and healthy subjects, regardless of the increment or decrement (50-ms MMN) condition. The MMN amplitudes were not correlated with depression symptoms. In addition, the peak latency of MMN amplitudes was longer in the MDD patients than the control subjects. These data indicate that pre-attentive information processing is impaired in MDD patients. This dysfunction may represent a trait of MDD patients rather than a state-dependent phenomenon.

Effects of acute nicotine on somatosensory change-related cortical responses

Nicotine is known to have enhancing effects on some aspects of attention and cognition. As for the pre-attentive processes of detecting sensory changes, nicotine has significant effects on the auditory and visual systems implying that its pre-attentive effect is common among sensory modalities. The purpose of the present study was to elucidate whether acute nicotine administration has enhancing effects in the somatosensory system. Change-related cortical activity in response to an abrupt increase in stimulus intensity was recorded using magnetoencephalography. The test stimulus consisted of standard electrical pulses at 100Hz for 500ms applied to the dorsum of the left hand followed by 0.7-mA stronger pulses for 300ms. Nicotine was administered in a gum (4mg of nicotine). Eleven healthy nonsmokers were tested with a double-blind and placebo-controlled design. Effects of nicotine on the cortical response in the primary (S1) and secondary (S2) somatosensory cortices were investigated. Results showed that nicotine failed to affect the S1 response while it significantly increased the amplitude of S2 activity in the hemisphere ipsilateral to the stimulation, and shortened the peak latency of S2 activity in both hemispheres. Since cortical responses in the present study represent a pre-attentive automatic process to encode new somatosensory events, the results suggest that nicotine can exert beneficial cognitive effects without a direct impact on attention and that the effect of nicotine on the automatic change-detecting system is common across sensory modalities.

Multisensory Representation of Frequency across Audition and Touch: High Density Electrical Mapping Reveals Early Sensory-Perceptual Coupling

The frequency of environmental vibrations is sampled by two of the major sensory systems, audition and touch, notwithstanding that these signals are transduced through very different physical media and entirely separate sensory epithelia. Psychophysical studies have shown that manipulating frequency in audition or touch can have a significant cross-sensory impact on perceived frequency in the other sensory system, pointing to intimate links between these senses during computation of frequency. In this regard, the frequency of a vibratory event can be thought of as a multisensory perceptual construct. In turn, electrophysiological studies point to temporally early multisensory interactions that occur in hierarchically early sensory regions where convergent inputs from the auditory and somatosensory systems are to be found. A key question pertains to the level of processing at which the multisensory integration of featural information, such as frequency, occurs. Do the sensory systems calculate frequency independently before this information is combined, or is this feature calculated in an integrated fashion during preattentive sensory processing? The well characterized mismatch negativity, an electrophysiological response that indexes preattentive detection of a change within the context of a regular pattern of stimulation, served as our dependent measure. High-density electrophysiological recordings were made in humans while they were presented with separate blocks of somatosensory, auditory, and audio-somatosensory "standards" and "deviants," where the deviant differed in frequency. Multisensory effects were identified beginning at ∼200 ms, with the multisensory mismatch negativity (MMN) significantly different from the sum of the unisensory MMNs. This provides compelling evidence for preattentive coupling between the somatosensory and auditory channels in the cortical representation of frequency.

Auditory Magnetic Response to Clicks in Children and Adults: Its Components, Hemispheric Lateralization and Repetition Suppression Effect

The auditory magnetic event-related fields (ERF) qualitatively change through the child development, reflecting maturation of auditory cortical areas. Clicks presented with long inter-stimulus interval produce distinct ERF components, and may appear useful to characterize immature EFR morphology in children. The present study is aimed to investigate morphology of the auditory ERFs in school-age children, as well as lateralization and repetition suppression of ERF components evoked by the clicks. School-age children and adults passively listened to pairs of click presented to the right ear, left ear or binaurally, with 8-11s intervals between the pairs and a 1s interval within a pair. Adults demonstrated a typical P50m/N100m response. Unlike adults, children had two distinct components preceding the N100m-P50m (at ~65ms) and P100m (at ~100ms). The P100m dominated the child ERF, and was most prominent in response to binaural stimulation. The N100m in children was less developed than in adults and partly overlapped in time with the P100m, especially in response to monaural clicks. Strong repetition suppression was observed for P50m both in children and adults, P100m in children and N100m in adults. Both children and adults demonstrated ERF amplitude and/or latency right hemispheric advantage effects that may reflect right hemisphere dominance for preattentive arousal processes. Our results contribute to the knowledge concerning development of auditory processing and its lateralization in children and have implications for investigation of the auditory evoked fields in developmental disorders.

Phonological processing differences in bilinguals and monolinguals

The present study examined whether monolinguals and balanced bilinguals perceive speech sounds similarly or whether the two phonological systems in bilinguals interact so that one language is affected by the other. Two groups, monolingual native speakers of Finnish and balanced Finnish–Swedish bilinguals, were tested. We measured mismatch negativity (MMN) responses and used individually selected, native language, stimuli. The results revealed that balanced bilinguals had a significantly longer MMN latency than the monolinguals which suggests slower and weaker preattentive processing in the bilinguals. This implies that the two phonological systems are intertwined which decreases the access of exemplars.