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Defensive reactions need to be quick and appropriate to ensure survival. So, it is crucial that threats trigger immediate action upon detection, even in the absence of awareness. Also, the form of such action should be appropriate to the imminence of the threat. Thus, attention should be guided by signals of increasing threat imminence. We examined whether subliminally presented threat stimuli provoke automatic avoidance tendencies and whether threat cues’ distance change and threat potential determine attention allocation. Following fear conditioning, participants performed an approach-avoidance task with subliminally presented conditioned threat and safety stimuli and an attentional bias task with approaching versus distancing signals of threat and safety. Pre-attentive processing of threat cues resulted in approach rather than avoidance tendencies; attention was captured preferentially by signals of increasing threat imminence. The results support the importance of threat imminence and extend findings of previous research on pre-attentive influences on defensive responding. ispartof: Emotion vol:17 issue:2 pages:251-258 ispartof: location:United States status: published

This study investigated the effect of hyperthermia on pre-attentive processing by recording the mismatch negativity (MMN) component of ERPs. 36 right-handed young male undergraduates were divided into two groups, a control group with 1h of exposure at 25°C and a heat group with 1h of exposure at 50°C. MMNs were recorded before and after heat exposure. It was found that, although there was no group difference before heat exposure, MMN declined significantly in the heat group compared to the control group after heat exposure for 1h, indicating that passive heat exposure could damage pre-attentive processing. The MMN component could be a good index to assess cognitive functioning in a hot environment.

Background Deficits of pre-attentive information processing have been frequently found in patients with major depressive disorder, nevertheless the results are quite inconsistent due to clinical heterogeneity and methodological difference. Cognitive processing of music is a useful tool for investigating human cognition and its underlying brain mechanisms. Although general auditory processing and perception of musical sound are hampered in patients with MDD, whether the deficits in musical processing begin from pre-attentive stage is not well investigated yet. The present study aimed to investigate the MMN of musical sound in patients with MDD. Method MMN responses to different musical features were compared in 20 patients with MDD and 20 age-matched healthy controls. The multi-feature paradigm was used to examine automatic change detection of six different musical sound features (pitch, timbre, location, intensity, slide, rhythm) in a complex musical context. Severity of depression and co-morbid anxiety were evaluated using the Hamilton Rating Scale of Depression (HRSD-17) and the Hamilton Anxiety Rating Scale (HAMA). Results MMNs were obtained with all deviants. The timbre-MMN was significantly larger in MDD patients than in healthy controls, while the other deviants (pitch, location, intensity, slide and rhythm) elicited similar MMN across groups. For MDD patients, the amplitudes and latencies of MMNs did not correlate with severity of depression or co-morbid anxiety. Limitations The sample size in this study is relatively small. Conclusion Patients with MDD do not perform at the same level as controls in automatic change detection of timbre. This dysfunction is considered to be a trait-dependent feature of MDD.

The purpose of the present study was to examine the role of trait anxiety and social desirability on skin conductance responses (SCRs) following exposure to masked and unmasked pictures in a non-clinical sample. The most prominent results were found with regard to masked pictures (i.e. subliminal). Higher levels of social desirability were associated with a decrease in SCRs to masked threat pictures (relative to neutral), whereas elevated levels of trait anxiety were associated with an increase in SCRs. This latter effect, however, was mainly seen among participants who simultaneously scored low on social desirability. These results were discussed in terms of trait anxiety (combined with lower social desirability scores) being associated with (i) enhanced autonomic responses to threatening information most evident at a pre-attentive level, that (ii) may potentially be a vulnerability marker for anxiety disturbances.

The present study was designed to test the hypothesis of unconscious attending to alcohol-related information in alcoholics experiencing a high level of craving for alcohol. Subjects included a group of alcoholics ( n =34) divided by a median split on a craving measure into two groups labeled as ‘high craving’ ( n =18) and ‘low craving’ ( n =16) alcoholics, and a non-alcoholic control group ( n =39). The cardiovascular reactions of these groups were compared after their exposure to masked and unmasked alcohol and control stimuli. As expected the ‘high craving’ alcoholics showed an immediate heart rate deceleration after exposure to masked and non-consciously accessible alcohol pictures. The ‘high craving’ alcoholics reported a small but significant increase in difficulty resisting a drink after exposure to masked alcohol pictures. When the alcohol pictures were presented unmasked a significant increase was found in both high and low craving alcoholics on consciously expressed urges, fidgeting and reduced coping with temptation to drink. The ‘high craving’ alcoholics had lower tonic heart rate variability compared to the control group and the level of craving was positively associated with salivation during the exposure to all picture types. The findings generally support the psychobiological theory of craving, which suggests that the uncontrollability of the craving experience is rooted in unconscious processing of drug-related information.

Neuronal mechanisms involved in the processing of complex sounds with asynchronous onsets were studied in reading subjects. The sound onset asynchrony (SOA) between the leading partial and the remaining complex tone was varied between 0 and 360 ms. Infrequently occurring deviant sounds (in which one out of 10 harmonics was different in pitch relative to the frequently occurring standard sound) elicited the mismatch negativity (MMN), a change-specific cortical event-related potential (ERP) component. This indicates that the pitch of standard stimuli had been pre-attentively coded by sensory-memory traces. Moreover, when the complex-tone onset fell within temporal integration window initiated by the leading-partial onset, the deviants elicited the N2b component. This indexes that involuntary attention switch towards the sound change occurred. In summary, the present results support the existence of pre-perceptual integration mechanism of 100-200 ms duration and emphasize its importance in switching attention towards the stimulus change.

Objective Despite ongoing debate about gender differences in pre-attention processes, little is known about gender effects on change detection for auditory and visual stimuli. We explored gender differences in change detection while processing duration information in auditory and visual modalities. Method We investigated pre-attentive processing of duration information using a deviant-standard reverse oddball paradigm (50ms/150ms) for auditory and visual mismatch negativity (aMMN and vMMN) in males and females ( n =21/group). Result In the auditory modality, decrement and increment aMMN were observed at 150–250ms after the stimulus onset, and there was no significant gender effect on MMN amplitudes in temporal or fronto-central areas. In contrast, in the visual modality, only increment vMMN was observed at 180–260ms after the onset of stimulus, and it was higher in males than in females. Conclusion No gender effect was found in change detection for auditory stimuli, but change detection was facilitated for visual stimuli in males. Significance Gender effects should be considered in clinical studies of pre-attention for visual stimuli.

Individuals frequently experience mental fatigue during or after prolonged periods of cognitive activity. We investigated the effects of mental fatigue on the ability to detect minor changes in the pre-attentive stage of information processing by recoding MMN of ERP components. The equal probable paradigm was employed to elicit pure memory-comparison-based MMN component. Mental fatigue was induced by the continuous performance for 2h of mental arithmetic tasks. MMN amplitudes at fronto-central electrode sites were significantly decreased in subjects with mental fatigue than in subjects under control conditions, whereas temporal MMN was not affected by mental fatigue. These results suggest that mental fatigue impairs pre-attentive processing.

Sixty-four children, aged 7 to 14 years, with early-treated PKU, were compared with control children on visual evoked potential (VEP) amplitudes and latencies and auditory mismatch negativity (MMN) amplitudes. It was further investigated whether indices of dietary control would be associated with these evoked potentials parameters. There were no significant differences between controls and children with PKU in VEP- and MMN-indices. However, higher lifetime Phe levels were, in varying degree and stronger than concurrent Phe level, related to increased N75 amplitudes, suggesting abnormalities in attention, and longer P110 latencies, indicating a reduction in speed of neural processing, possibly due to deficits in myelination or reduced dopamine levels in brain and retina. Similarly, higher lifetime Phe levels and Index of Dietary Control (IDC) were associated with decreased MMN amplitudes, suggesting a reduced ability to respond to stimulus change and poorer triggering of the frontally mediated attention switch. In summary, the present study in children with PKU investigated bottom-up information processing, i.e., triggered by external events, a fundamental prerequisite for the individual's responsiveness to the outside world. Results provide evidence that quality of dietary control may affect the optimal development of these pre-attentive processes, and suggest the existence of windows of vulnerability to Phe exposure.

We compared the pre-attentive processing in patients with a major depressive disorder (MDD) and matched healthy controls as indexed by the visual mismatch negativity (vMMN) elicited by exposure duration of visual stimuli randomly presented on both peripheral visual fields. To obtain the memory-comparison-based visual MMN, the role of standard and deviant stimuli was reversed in separate blocks. Compared with healthy participants, MDD patients exhibited decreased MMN amplitudes of long duration deviant only and this deficit was not correlated with the depression severity. These data suggests functional impairment of pre-attentive basic visual information processing in MDD patients.

Previous studies have reported seemingly conflicting results regarding how the amount of stimulus similarity between two simultaneously presented target stimuli impacts perceptual performance. There are many reports of ‘repetition blindness’, where individuals do worse when shown two similar stimuli relative to two different stimuli. On the other hand, there are reports of ‘similarity grouping’, where participants perform better when identifying two similar objects relative to two different objects. This manuscript posits that repetition blindness and similarity grouping coexist and can be elicited in the same subjects in a single task. This not only explains the previous opposite effects of stimulus similarity on task performance, but also provides a unique opportunity to directly compare these opposite effects of stimulus similarity with respect to susceptibility to a modulating factor. Since previous studies have provided inconclusive results on whether attentional relevance can modulate the effect of stimulus similarity on task performance, the current manuscript aims to compare repetition blindness and similarity grouping with respect to their susceptibility to attentional relevance. The results of the first experiment confirmed that both repetition blindness and similarity grouping can be elicited in the same experiment, suggesting that repetition blindness and similarity grouping coexist. The results of the second experiment suggest that both repetition blindness and similarity grouping can be modulated by attentional relevance. These results support the explanation of repetition blindness as a token individuation failure. Furthermore, these results suggest that supposedly pre-attentional grouping mechanisms might not operate as independently from top-down attentional modulations as traditionally thought.

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.

Is apparent object size represented in pre-attentive vision and can it influence visual search for size-defined targets in a spatially parallel manner? This question was investigated, using the Muller-Lyer illusion. Observers searched for a target line that was longer than the distractor lines. Test lines could be presented without context arrows (control); be adjoined by obtuse-angle context arrows (arrow heads pointing inward), making the lines appear longer; or by acute-angle arrows (heads pointing outward), making the lines appear shorter. These apparent-length modulations were larger for the target than for the distractor lines, thereby increasing and, respectively, decreasing the target-distractor length contrast. In line with these changes in contrast, target detection was found to be expedited by obtuse-angle arrows and impeded by acute-angle arrows, independently of the number of elements in the display. This finding provides further evidence for the pre-attentive processing of apparent object size.

The main goal of this review is to elucidate up to what extent pre-attentive auditory information processing is affected during human sleep. Evidence from event-related brain potential (ERP) studies indicates that auditory information processing is selectively affected, even at early phases, across the different stages of sleep-wakefulness continuum. According to these studies, 3 main conclusions are drawn: (1) the sleeping brain is able to automatically detect stimulus occurrence and trigger an orienting response towards that stimulus if its degree of novelty is large; (2) auditory stimuli are represented in the auditory system and maintained for a period of time in sensory memory, making the automatic-change detection during sleep possible; and (3) there are specific brain mechanisms (sleep-specific ERP components associated with the presence of vertex waves and K-complexes) by which information processing can be improved during non-rapid eye movement sleep. However, the remarkably affected amplitude and latency of the waking-ERPs during the different stages of sleep suggests deficits in the building and maintenance of a neural representation of the stimulus as well as in the process by which neural events lead to an orienting response toward such a stimulus. The deactivation of areas in the dorsolateral pre-frontal cortex during sleep contributing to the generation of these ERP components is hypothesized to be one of the main causes for the attenuated amplitude of these ERPs during human sleep.

A. Oehman and J. J. F. Soares (1994) demonstrated that masked presentation of phobic pictures produces increased skin conductance responses (SCRs) in phobic Ss. Oehman (1993) explained this phenomenon in terms of a hypothetical "feature detector" that identifies physical characteristics of stimuli and activates the arousal system without involving significance evaluation or consciousness. This explanation was tested by exposing 41 Ss with spider phobia (mean age 32 yrs) to spider words, general threat words, and neutral words instead of pictures. Words were presented both masked and unmasked while electrodermal activity was measured. Under unmasked conditions, SCRs were largest for spider words followed by general threat words, then neutral words. When masked, the difference between spider words and general threat words disappeared but SCRs remained significantly smaller for neutral words. The authors conclude that activation of the arousal system by masked threat cues does not necessarily depend on their perceptual characteristics.

Feature singleton search is faster when the target-defining dimension is repeated, rather than changed, across trials (Found & Müller, 1996). A similar dimension repetition benefit has been observed in a non-search (discrimination) task with a single stimulus (Mortier, Theeuwes, & Starreveld, 2005). Two experiments examined whether these effects in the two tasks originate from the same or different processing stages. Experiment 1 revealed differential feature-specific effects, and Experiment 2 differential processing of dimensionally redundant target signals between the two types of task. These dissociations support the existence of separable, pre-attentive and post-selective sources of inter-trial effects in the two tasks.

In a dichotic listening situation stimuli were presented one at a time and at random to either ear of the subject at constant inter-stimulus intervals of 800 msec. The subject's task was to detect and count occasional slightly different stimuli in one ear. In Experiment 1, these ‘signal’ stimuli were slightly louder, and in Experiment 2 they had a slightly higher pitch, than the much more frequent, ‘standard’, stimuli. In both experiments signals occured randomly at either ear. Separate evoked potentials from three different locations were recorded for each of the four kinds of stimuli (attended signals, unattended signals, attended standards, unattended standards). Contrary to Hillyard et al. (1973), no early (N 1 component) evoked-potential enhancement was observed to stimuli to the attended ear as compared with those to the unattended ear, but there was a later negative shift superimposed on potentials elicited by the former stimuli. This negative shift was considered identical to the N 1 enhancement of Hillyard and his colleagues which in the present study was forced, by the longer inter-stimulus interval used, to demonstrate temporal dissociation with the N 1 component. The ‘Hillyard effect’ was, consequently, explained as being caused by a superimposition of a CNV kind of negative shift on the evoked potential to the attended stimuli rather than by a growth of the ‘real’ N 1 component of the evoked potential.