Automatic change detection and spatial attention: a visual mismatch negativity study.

Visual mismatch negativity (vMMN) is the electrophysiological correlate of automatic detection of unattended changes in the visual environment. However, vMMNs' relatedness to spatial attention has not been explicitly tested. Thus, the aim of the study was to investigate the effects of spatial attention on the vMMN event-related potential component. To this end, participants were instructed to fixate and attend to task-related stimuli. In an oddball sequence, offset stimuli were applied, i.e., from time-to time, the two sides of permanently presented objects disappeared. Distance between the task-related and unrelated events resulted in the typical finding of spatial attention; the amplitude of the N1 component was larger at the shorter distance between the two kinds of events. VMMN was elicited by the deviant vanishing parts, with no reliable effect of distance between the task-field and vMMN-related stimuli. In terms of the difference potentials, vMMN was followed by a positive posterior component in the 270-330 ms range. This positivity was much larger when the task-field was close to vMMN-related stimuli. The reappearance of the vanishing parts was also investigated. The reappearance of the whole objects after a deviant offset elicited vMMN but only when the task-field was close to the oddball sequence. We concluded that infrequently vanishing parts of objects are detected automatically. However, these deviant events initiate orientation only if the objects are close to the field of task-relevant events. Similarly, automatic registration of the rare but expected events are registered only in the visual field close to the focus of attention.

Visual mismatch negativity and stimulus-specific adaptation: the role of stimulus complexity.

The present study investigated the function of the brain activity underlying the visual mismatch negativity (vMMN) event-related potential (ERP) component. Snowflake patterns (complex stimuli) were presented as deviants and oblique bar patterns (simple stimuli) as standards, and vice versa in a passive oddball paradigm. Control (equiprobable) sequences of either complex shape patterns or oblique bar patterns with various orientations were also presented. VMMN appeared as the difference between the ERP to the oddball deviant and the ERP to the control (deviant minus control ERP difference). Apart from the shorter latency of the vMMN to the oblique bar pattern as deviant, vMMN to both deviants was similar, i.e., there was no amplitude difference. We attributed the function of the brain processes underlying vMMN to the detection of the infrequent stimulus type (also represented in memory) instead of a call for further processing (a possibility for acquiring more precise representation) of the deviant. An unexpected larger adaptation (control minus standard ERP difference) to the snowflake pattern was also obtained. We suggest that this was due to the acquisition of a more elaborate memory representation of the more complex stimulus.

Visual mismatch negativity to disappearing parts of objects and textures.

Visual mismatch negativity (vMMN), an event-related signature of automatic detection of events violating sequential regularities is traditionally investigated at the onset of frequent (standard) and rare (deviant) events. In a previous study we obtained vMMN to vanishing parts of continuously presented objects (diamonds with diagonals), and we concluded that the offset-related vMMN is a model of sensitivity to irregular partial occlusion of objects. In the present study we replicated the previous results, but in order to test the object-related interpretation we applied a new condition with a set of separate visual stimuli: a texture of bars with two orientations. In the texture condition (offset of bars with irregular vs. regular orientation) we obtained vMMN, showing that the continuous presence of objects is unnecessary for offset-related vMMN. However, unlike in the object-related condition, reappearance of the previously vanishing lines also elicited vMMN. In principle reappearance of the stimuli is an event with probability 1.0, and according to our results, the object condition reappearance was an expected event. However, the offset and onset of texture elements seems to be treated separately by the system underlying vMMN. As an advantage of the present method, the whole stimulus set during the inter-stimulus interval saturates the visual structures sensitive to stimulus input. Accordingly, the offset-related vMMN is less sensitive to low-level adaptation that differs between the deviant and standard stimuli.

Automatic Change Detection in Older and Younger Women: A Visual Mismatch Negativity Study.

BACKGROUND: In comparison to controlled (attentional) processing, relatively little is known about the age-related changes of the earlier (preattentive) processes. An event-related potential (ERP) index of preattentive (automatic) visual processing, the visual mismatch negativity (vMMN) is a good candidate for analyzing age-related differences in the automatic processing of visual events. OBJECTIVE: So far results concerning age-related changes in vMMN have been equivocal. Our aim was to develop a method resulting in a reliable vMMN in a paradigm short enough to use in the applied field. METHODS: We investigated an older (mean age: 66.4 years, n = 15) and a younger (mean age: 22.4 years, n = 15) group of healthy women. ERPs were obtained for checkerboard onset patterns in a passive oddball condition (during which participants performed a tracking task). One of the checkerboards was frequent (standard; p = 0.8), and the other was rare (deviant; p = 0.2). RESULTS: vMMN emerged over posterior locations in the latency range of 100-300 ms in both age groups. The amplitude of the earlier part of the vMMN was similar in the older and the younger participants, but latency was longer in the older group. The later part of the vMMN was slightly diminished in the elderly. CONCLUSION: Automatic detection of violated sequential regularities, reflected by the vMMN, emerged in the two age groups (earlier vMMN). However, detection of stimulus change, a preattentive visual process delayed in the elderly, and identification of the specific change was compromised in the older participants.

Automatic detection of the duration of visual static and dynamic stimuli.

The perception of the passing of time is fundamental to conscious experience. The duration of a sensory stimulus is one of its defining attributes, but it is not clear how this is encoded in the brain. This work explores whether the duration of a visual stimulus is an attribute that the brain can automatically adapt to and use to predict future stimulus durations. Visual mismatch negativity (vMMN) is an ERP component elicited, even when the stimuli are unattended, when an 'unexpected' visual stimulus appears amongst a series of expected stimuli in an 'oddball' paradigm. As such vMMN has been suggested to show that the violation of a pattern in a sequence has been automatically detected. To date, vMMN has only been measured to differences in the visual durations of static on/off stimuli, placed near to the centre of the visual field. Our study measures vMMN to test whether duration is encoded automatically for static stimuli against a blank background and moving stimuli against a static background, whilst attention is directed to a different spatial location using a continuous, attention demanding task. VMMN elicited in response to the shorter duration for both stimuli shows that the brain detects the differences of duration even in the absence of focussed spatial attention. For the motion stimulus a larger difference in duration was needed. We conclude that duration is encoded automatically in the visual cortex and is an attribute that can be adapted to, and form the basis of predictions.

Visual mismatch negativity to vanishing parts of objects in younger and older adults.

We investigated visual mismatch negativity (vMMN) to vanishing parts of continuously present objects by comparing the event-related potentials (ERPs) to infrequently (deviant) and frequently (standard) disappearing parts of the objects. This paradigm both excludes low-level stimulus-specific adaptation differences between the responses to deviants and standards, and increases the ecological validity of the stimuli. In comparison to frequently disappearing parts of the stimulus objects, infrequently vanishing parts elicited posterior negative event-related brain activity (vMMN). However, no vMMN emerged to the reappearance of the same parts of the objects. We compared the ERPs of an older and a younger sample of participants. In the 120-180 ms time period vMMN was similar in the two age groups, but in the 180-220 ms time period vMMN emerged only in the younger participants. We consider this difference as an index of more elaborate automatic processing of infrequent stimulus changes in younger adults.

Automatic change detection in vision: Adaptation, memory mismatch, or both? II: Oddball and adaptation effects on event-related potentials.

In this study we compared the event-related potentials (ERPs) obtained in two different paradigms: a passive visual oddball paradigm and an adaptation paradigm. The aim of the study was to investigate the relation between the effects of activity decrease following an adaptor (stimulus-specific adaptation) and the effects of an infrequent stimulus within sequences of frequent ones. In Experiment 1, participants were presented with different line textures. The frequent (standard) and rare (deviant) texture elements differed in their orientation. In Experiment 2, windmill pattern stimuli were presented in which the number of vanes differentiated the deviant and standard stimuli. In Experiment 1 the ERP differences elicited between the oddball deviant and the standard were similar to the differences between the ERPs to the nonadapted and adapted stimuli in the adaptation paradigm. In both paradigms the differences appeared as a posterior negativity with the latency of 120-140 ms. This finding demonstrates that the representation of a sequential rule (successive presentation of the standard) and the violation of this rule are not necessary for deviancy effects to emerge. In Experiment 2 (windmill pattern), in the oddball paradigm the difference potentials appeared as a long-lasting negativity. In the adaptation condition, the later part of this negativity (after 200 ms) was absent. We identified the later part of the oddball difference potential as the genuine visual mismatch negativity-that is, an ERP correlate of sequence violations. The latencies of the difference potentials (deviant minus standard) and the endogenous components (P1 and N1) diverged; therefore, the adaptation of these particular ERP components cannot explain the deviancy effect. Accordingly, the sources contributing to the standard-versus-deviant modulations differed from those related to visual adaptation; that is, they generated distinct ERP components.

Automatic detection of orientation variance.

Rapid extraction of the overall statistics of the visual scene is crucial for the human ability to rapidly perceive the general 'gist'. The aim of this work was to investigate if there exists neural evidence for such a process i.e. automatic, unattended detection of overall statistical differences between scenes. In order to do this, Visual Mismatch Negativity (vMMN), an early evoked neural response component, was measured. We presented a sequence of sets of oriented patterns of a given (random) mean orientation and varied the variance of the orientations of the patterns, so that some sets contained similar orientations (ordered) or the orientations were random (disordered). These two types of sets of patterns were presented in an oddball sequence such that one type occurred often and the other was a rare, unexpected stimulus. We found a significant vMMN in response to a randomly oriented stimulus amongst more ordered stimuli, which suggested that humans perceive 'ordered' vs 'disordered' scenes categorically. We conclude that by manipulating the variance of the orientations contained within each stimulus we are able to show that this property is automatically encoded in visual neural response.

Visual mismatch negativity (vMMN) for low- and high-level deviances: A control study.

The aim of our studies was to separate the effects of violating a sequential rule (genuine visual mismatch negativity; gvMMN) from the decreased activity in response to repeated stimuli (stimulus-specific adaptation; SSA) for simple and more complex stimuli. To accomplish this goal, different control procedures were applied with the aim of finding the correct control for vMMN studies. Event-related brain electric activity (ERPs) was measured in response to nonattended visual stimuli that were presented either in an oddball manner or in various control sequences. To identify the cortical sources of the different processes, the sLORETA inverse solution was applied to the average ERP time series. In Experiment 1, the stimuli were line textures, and the deviancy was different line orientations. SSA fully explained the deviant-related ERP effects (increased posterior negativity in the 105-190 ms range). In Experiments 2 and 3, windmill patterns were used. Infrequent windmill patterns with 12 vanes elicited gvMMN (posterior negativities in the 100-200 and 200-340 ms ranges), whereas in the case of the less complex (six vanes) stimuli, SSA explained the negative deflection in both latency ranges (178-216 and 270-346 ms). In Experiment 3, infrequent stimuli with six vanes elicited deviant-related posterior negativity within the sequence of less complex (four vanes) frequent patterns. We reconcile the discrepant results by proposing that the underlying processes of vMMN are not uniform but depend strongly on the eliciting stimulus and that the complexity difference between the infrequent and frequent stimuli has considerable influence on the deviant-related response.

Asymmetric effect of automatic deviant detection: The effect of familiarity in visual mismatch negativity.

The visual mismatch negativity (vMMN) component is regarded as a prediction error signal elicited by events violating the sequential regularities of environmental stimulation. The aim of the study was to investigate the effect of familiarity on the vMMN. Stimuli were patterns comprised of familiar (N) or unfamiliar (И) letters. In a passive oddball paradigm, letters (N and И) were presented as either standard or deviant in separate conditions. VMMNs emerged in both conditions; peak latency of vMMN was shorter to the И deviant compared to the vMMN elicited by the N deviant. To test the orientation-specific effect of the oblique lines on the vMMN, we introduced a control experiment. In the control experiment, the patterns were constructed solely from oblique lines, identical to the oblique lines of the N and И stimuli. Contrary to the first experiment, there was no significant difference between the vMNNs elicited by the two orientations. Therefore, the differences in vMMNs to И and N deviants are not attributable to the physical difference between the И and N stimuli. Consequently, the vMMN is sensitive to the familiarity of the stimuli. This article is part of a Special Issue entitled SI: Prediction and Attention.

Visual mismatch negativity is sensitive to illusory brightness changes.

The aim of the study was to investigate the sensitivity of the visual mismatch negativity (vMMN) component of event-related potentials (ERPs) to the perceptual experience of brightness changes. The percept could be based on either real contrast or illusory brightness changes. In the illusory condition, we used Craik-Cornsweet-O׳Brien (CCOB) stimuli. CCOB stimuli comprised of grey, equiluminant areas and Cornsweet-edges that separated the areas. These specific edges, containing opposing darkening and ligthening gradients, modify the perceived brigthness of the flanking areas. Areas next to the darkening part (of the edges) perceived darker while areas next to the lightening part perceived lighter. Reversing the gradients induces illusory brigthness changes. The normal and reversed stimuli were delivered according to a passive oddball paradigm. In another condition (REAL condition), we used stimuli with real contrast difference. The perceived brightness of the stimuli applied in this sequence was fitted to the normal and reversed CCOB stimuli. In a third condition (CONTROL condition), we tested the ERP effect of the reversing of Cornsweet-edge. In this condition, the changes did not induce illusory brightness changes. We obtained vMMN with double peaks to both real and illusory brigthness changes, furthermore, no vMMN emerged in the CONTROL condition. vMMNs fell in the same latency range in the two conditions, nevertheless the components slightly differed in terms of scalp distribution. Since the perceptual experience (i.e. brightness changes) was similar in the two conditions, we argue that the vMMN is primarily sensitive to the perceptual experience and the physical attributes of the stimulation has only a moderate effect in the elicitation of the vMMN.

Asymmetry of automatic change detection shown by the visual mismatch negativity: an additional feature is identified faster than missing features.

In two experiments, we demonstrated that an asymmetric effect of the brain electric activity that is elicited by nonattended visual stimuli is similar to the one found in responses observed in the performance of visual search tasks. The automatic detection of violated sequential regularities was investigated by measuring the visual mismatch negativity (vMMN) component of event-related brain potentials (ERPs). In Experiment 1, within a sequence of stimulus displays with O characters, infrequently presented Q characters elicited an earlier vMMN than did infrequent O characters within a sequence of Q characters. In Experiment 2, similar asymmetric results emerged if only 16% of the characters were different within an infrequent display. In both experiments, these stimuli were irrelevant; during the stimulus sequences, participants performed a demanding videogame. We suggest that the underlying match/mismatch and decision processes are similar in the vMMN and in the attention-related visual search paradigm, at least in the case of the stimuli in the present experiments.

Is it a face of a woman or a man? Visual mismatch negativity is sensitive to gender category.

The present study investigated whether gender information for human faces was represented by the predictive mechanism indexed by the visual mismatch negativity (vMMN) event-related brain potential (ERP). While participants performed a continuous size-change-detection task, random sequences of cropped faces were presented in the background, in an oddball setting: either various female faces were presented infrequently among various male faces, or vice versa. In Experiment 1 the inter-stimulus-interval (ISI) was 400 ms, while in Experiment 2 the ISI was 2250 ms. The ISI difference had only a small effect on the P1 component, however the subsequent negativity (N1/N170) was larger and more widely distributed at longer ISI, showing different aspects of stimulus processing. As deviant-minus-standard ERP difference, a parieto-occipital negativity (vMMN) emerged in the 200-500 ms latency range (~350 ms peak latency in both experiments). We argue that regularity of gender on the photographs is automatically registered, and the violation of the gender category is reflected by the vMMN. In conclusion the results can be interpreted as evidence for the automatic activity of a predictive brain mechanism, in case of an ecologically valid category.

Oblique effect in visual mismatch negativity.

We investigated whether visual orientation anisotropies (known as oblique effect) exist in non-attended visual changes using event-related potentials (ERP). We recorded visual mismatch negativity (vMMN) which signals violation of sequential regularities. In the visual periphery unattended, task-irrelevant Gábor patches were displayed in an oddball sequence while subjects performed a tracking task in the central field. A moderate change (50°) in the orientation of stimuli revealed no consistent change-related components. However, we found orientation-related differences around 170 ms in occipito-temporal areas in the amplitude of the ERPs evoked by standard stimuli. In a supplementary experiment we determined the amount of orientation difference that is needed for change detection in an active, attended paradigm. Results exhibited the classical oblique effect; subjects detected 10° deviations from cardinal directions, while threshold from oblique directions was 17°. These results provide evidence that perception of change could be accomplished at significantly smaller thresholds, than what elicits vMMN. In Experiment 2 we increased the orientation change to 90°. Deviant-minus-standard difference was negative in occipito-parietal areas, between 120 and 200 ms after stimulus onset. VMMNs to changes from cardinal angles were larger and more sustained than vMMNs evoked by changes from oblique angles. Changes from cardinal orientations represent a more detectable signal for the automatic change detection system than changes from oblique angles, thus increased vMMN to these "larger" deviances might be considered a variant of the magnitude of deviance effect rarely observed in vMMN studies.

Visual mismatch negativity is sensitive to symmetry as a perceptual category.

We investigated the sensitivity of visual mismatch negativity (vMMN) to an abstract and non-semantic category, vertical mirror symmetry. Event-related potentials (ERPs) elicited by random and symmetric square patterns, delivered in passive oddball paradigm (participants played a video game), were recorded. In one of the conditions, symmetric patterns were frequent (standard) stimuli and the random patterns were infrequent (deviant) stimuli; in the other condition, the probabilities were reversed. We compared the ERPs elicited by symmetric stimuli as deviants and as standards, and, similarly, the ERPs elicited by the random deviants and random standards. As the difference between the ERPs elicited by random deviant and random standard stimuli, a posterior negativity emerged in two latency ranges (112-120 and 284-292 ms). These negativities were considered to be vMMN components. We suggest that the two vMMN components are organised in cascade error signals. However, there was no significant difference between the ERPs elicited by symmetric deviants and those elicited by symmetric standards. The emergence of vMMN in response to the deviant random stimuli is considered to be a deviation of a perceptual category (in the symmetric standard sequence presented). Accordingly, random stimuli acquired no perceptual category; for this reason, the symmetric deviant (in the random standard sequence presented) elicited no vMMN. The results show that the memory system underlying vMMN is capable of coding perceptual categories such as bilateral symmetry, even if the stimulus patterns are unrelated to the ongoing behavior.

One plus one is less than two: visual features elicit non-additive mismatch-related brain activity.

In a passive oddball task (performing in a video game), participants were presented with sequences of either standard stimuli or patterns containing deviant orientation, deviant spatial frequency or both deviant orientation and spatial frequency. Orientation deviants presented to the lower half of the visual field elicited a posterior negative component with a peak latency of 130 ms. Spatial frequency deviants elicited a similarly negative component that was later followed by another negative component. Activity elicited by the double-deviant stimulus was identical to activity elicited by the orientation deviant alone. The subtraction difference of the peak latency and scalp distribution of the deviant minus the standard difference potentials were unequal to those of the exogenous event-related potential (ERP) components and were therefore considered visual mismatch negativities (vMMNs). The non-additivity of the feature-related responses is interpreted as sensitivity of the implicit change-detection system to deviant events rather than an exclusive sensitivity to individual features. Deviant stimuli presented to the upper half of the field elicited responses with positive polarity, but this activity was less pronounced than the vMMN. Polarity reversal of the response to upper half-field stimulation suggests that the origin of the activity lies in retinotopic areas. Because of the emergence of a mismatch component with positive polarity, we propose that the term visual mismatch negativity (vMMN) be replaced with the more general term visual mismatch response (vMMR).

Visual mismatch negativity to irrelevant changes is sensitive to task-relevant changes.

Event-related potentials (ERPs) were measured in response to frequent (standard) and infrequent (deviant) task-irrelevant bar patterns. The constituent bars of the deviant patterns had either different orientation or different color than the bars of the standard. The task was the detection of either the orientation or the color change of a centrally presented shape. The deviant minus the standard ERP difference produced posterior negativity and was identified as visual mismatch negativity (vMMN). On the one hand, vMMN to orientation deviancy had smaller amplitude in the task demanding detection of the orientation change, and vMMN to color deviancy had smaller amplitude in the task demanding the color change. On the other hand, irrelevant deviancy influenced the task-performance. Reaction time (RT) to the orientation change of the target shape was longer in sequences with orientation change in the background, whereas RT to color change was longer in sequences with color change in the background. This interaction suggested that there was competition between the processing of irrelevant stimuli that share characteristics of task-related changes and target-related processing.