Temporal regularity effects on pre-attentive and attentive processing of deviance

Temporal regularity allows predicting the temporal locus of future information thereby potentially facilitating cognitive processing. We applied event-related brain potentials (ERPs) to investigate how temporal regularity impacts pre-attentive and attentive processing of deviance in the auditory modality. Participants listened to sequences of sinusoidal tones differing exclusively in pitch. The inter-stimulus interval (ISI) in these sequences was manipulated to convey either isochronous or random temporal structure. In the pre-attentive session, deviance processing was unaffected by the regularity manipulation as evidenced in three event-related-potentials (ERPs): mismatch negativity (MMN), P3a, and reorienting negativity (RON). In the attentive session, the P3b was smaller for deviant tones embedded in irregular temporal structure, while the N2b component remained unaffected. These findings confirm that temporal regularity can reinforce cognitive mechanisms associated with the attentive processing of deviance. Furthermore, they provide evidence for the dynamic allocation of attention in time and dissociable pre-attentive and attention-dependent temporal processing mechanisms.     

Temperament, anxiety, and the processing of threat-relevant stimuli.

This article discusses converging evidence from developmental, clinical, and cognitive psychology suggesting that there is significant overlap between research findings on affect, temperament, and attentional processes associated with pathological anxiety. We offer a proposal for the integration of these 3 areas aimed at developing a more clear understanding of the developmental sequence and operative mechanisms in the dysregulation of negative affect and the development of symptoms of anxiety pathology. We review evidence for a model indicating that reactive and effortful temperamental processes, possibly mediated by an attentional bias toward threat-relevant information, interact to produce problems of dysregulated negative affect and elevated levels of pathological anxiety. This model may assist in understanding the development of anxiety disorders, identifying children at risk for such disorders, and selecting points of entry for both preventative and curative interventions.     

Masked fear words produce increased SCRs: an anomaly for Ohman's theory of pre-attentive processing in anxiety

A. Ohman and J.J.F. Soares (1994) demonstrated that masked presentation of phobic pictures produces increased skin conductance responses (SCRs) in phobic subjects. A. Ohman (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. By exposing spider phobics to spider words, general threat words, and neutral words instead of pictures, this explanation was tested. 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. It is concluded that activation of the arousal system by masked threat cues does not necessarily depend on their perceptual characteristics.     

Parallel processing of affective visual stimuli

Event-related potential (ERP) studies of affective picture processing have demonstrated an early posterior negativity (EPN) for emotionally arousing pictures that are embedded in a rapid visual stream. The present study examined the selective processing of emotional pictures while systematically varying picture presentation rates between 1 and 16 Hz. Previous results with presentation rates up to 5 Hz were replicated in that emotional compared to neutral pictures were associated with a greater EPN. Discrimination among emotional and neutral contents was maintained up to 12 Hz. To explore the notion of parallel processing, convolution analysis was used: EPNs generated by linear superposition of slow rate ERPs explained 70%–93% of the variance of measured EPNs, giving evidence for an impressive capacity of parallel affective discrimination in rapid serial picture presentation.     

Cardiac responses associated with affective processing of unpleasant film stimuli.

The autonomic basis of cardiac reactions to unpleasant film stimuli was investigated. Film clips depicting major surgery, threats of violence, and neutral material were presented to 46 subjects. Self-report measures of emotion were obtained, as well as heart rate, respiration rate, respiratory sinus arrhythmia, T-wave amplitude and skin conductance level. Resting vagal tone was estimated in a paced breathing task prior to film viewing. Spontaneous blink rate was also taken as a measure of visual engagement during film viewing. Coherent increases in sympathetic activation accompanied the film containing violent threats, whereas the surgery film yielded greater electrodermal activation, as well as heart rate deceleration and T-wave increase. These data support the hypothesis of differential autonomic response patterns to specifically unpleasant material. As compared with threat and neutral films, greater blink rate inhibition was observed during the surgery film. Individual differences in parasympathetic cardiac control measured at rest were able to discriminate cardiac response patterns during film viewing.     

ERP correlates of pre-attentive processing of Cantonese lexical tones: The effects of pitch contour and pitch height

The pre-attentive processing of Cantonese tones was studied with an auditory passive oddball paradigm. Event-related potentials to standard and deviant auditory stimuli were recorded as participants watched a silent movie attentively. The standards and deviants differed in either pitch level or pitch contour. Mismatch negativity (MMN) and P3a were elicited by all types of deviant tones, suggesting that lexical tone was processed pre-attentively. In addition, the size and latency of MMN were sensitive to the size of pitch level change, while the latency of P3a captured the presence of pitch contour change. These results indicate that pitch contour and pitch height are two important dimensions in sensory processing of lexical tones.     

Regional cerebral blood flow increases during preparation for and processing of sensory stimuli

 Preparing for and processing of sensory stimuli are energy-requiring processes. We attempted to assess the relative contributions of these processes to increases in regional cerebral perfusion. Nineteen healthy right-handed subjects were examined while they were engaged in detecting tactile stimuli to the index finger 5 s after a cueing tone. Cerebral blood flow velocity (CBFV) modulations in the middle cerebral arteries (MCAs) were continuously measured by bilateral simultaneous transcranial Doppler ultrasonography. Tactile stimuli well above threshold per se did not produce a significant, relative CBFV increase in the contralateral MCA. However, when subjects were expecting a threshold tactile stimulus, there was a significant regional increase in CBFV in the hemisphere contralateral to the attended index finger for approximately 15 s, starting within the first seconds after the cueing. This increase was present even before the tactile stimulus was applied and also in sessions when the stimulus was omitted. We conclude that preparation of the cortex causes a stronger regional cerebral blood flow increase than the processing of the tactile stimulus itself. Received: 1 August 1996 / Accepted: 7 March 1997     

Vertical asymmetries in pre-attentive detection of changes in motion direction.

Stimulus localization affects visual motion processing. Vertical asymmetries favouring lower visual field have been reported in event-related potentials (ERPs) and behavioural studies under different attention conditions. However, there are no studies examining such asymmetries to non-attended motion changes. The present study investigated whether the asymmetry in processing information from the upper and lower visual fields also affects the automatic detection of motion-direction changes as indexed by visual Mismatch Negativity (vMMN). We recorded vMMN to changes in sinusoidal gratings differing in motion direction presented in the periphery of visual field in three different locations: upper and lower (ULVF), upper (UVF) and lower (LVF) along the vertical meridian. The N2 component elicited to peripheral motion presented lower amplitudes when the UVF was stimulated. The vMMN elicited to infrequent motion-direction changes was present in all stimulation conditions. However, it was reduced to UVF stimulation. These results suggest that the visual system automatically detects motion-direction changes presented at both upper-lower visual fields; however they also indicate that the process is favoured when stimuli are presented in the LVF alone.     

Perceptual load modifies processing of unattended stimuli both in the presence and absence of attended stimuli

This study explored effects of perceptual load on stimulus processing in the presence and absence of an attended stimulus. Participants were presented with a bilateral or unilateral display and asked to perform a discrimination task at either low or high perceptual load. Electrophysiological responses to stimuli were then compared at the P100 and N100. As in previous studies, perceptual load modified processing of attended and unattended stimuli seen at occipital scalp sites. Moreover, perceptual load modulated attention effects when the attended stimulus was presented at high perceptual load for unilateral displays. However, this was not true when the attended and unattended stimulus appeared simultaneously in bilateral displays. Instead, only a main effect of perceptual load was found. Reductions in processing contralateral to the unattended stimulus at the N100 provide support for Lavie's (1995) theory of selective attention.     

Attachment state of mind and perceptual processing of emotional stimuli

This study aimed to investigate the relationship between attachment state of mind and perceptual processing of social and non-social, affective, and neutral material. A total of 57 young adults completed the Adult Attachment Interview (AAI) plus an experimental task in which their perceptual thresholds to different types of pictures were assessed. Significant correlations were found between the AAI dimensions and perceptual thresholds for social stimuli such as social interactions or human faces displaying emotional expressions. As expected, no relationships were found between the AAI and perception of neutral stimuli. The pattern of correlations was especially clear for the dismissing dimension. The results suggest that higher vigilance to social stimuli is related to dismissing attachment tendencies and, to a milder degree, to preoccupied tendencies.     

Attachment state of mind and perceptual processing of emotional stimuli

This study aimed to investigate the relationship between attachment state of mind and perceptual processing of social and non-social, affective, and neutral material. A total of 57 young adults completed the Adult Attachment Interview (AAI) plus an experimental task in which their perceptual thresholds to different types of pictures were assessed. Significant correlations were found between the AAI dimensions and perceptual thresholds for social stimuli such as social interactions or human faces displaying emotional expressions. As expected, no relationships were found between the AAI and perception of neutral stimuli. The pattern of correlations was especially clear for the dismissing dimension. The results suggest that higher vigilance to social stimuli is related to dismissing attachment tendencies and, to a milder degree, to preoccupied tendencies.     

Preattentive processing of feared stimuli in blood-injection-injury fearful subjects

This research aimed to study the defence responses of blood-injection-injury (BII) fearful subjects elicited by the preattentive processing of their feared objects and by an abrupt acoustic stimulus. We selected 21 BII fearful subjects and 25 non-fearful controls from an initial sample of 128 women, according to their scores on the Fear Survey Scale (damage subscale) and the Mutilation Questionnaire. Subjects were exposed to a burst of white noise to promote a defence response, and to 48 pictures, depicting mutilations, as well as other affective contents, displayed through a backward masking procedure. Heart rate (HR), skin conductance response (SCR) and corrugator supercilii activity were continuously recorded throughout the task. Both groups showed similar SCRs, EMG activity and cardiac defence responses to the acoustic stimulus, though fearful subjects showed greater initial HR deceleration than controls. While BII fearful subjects displayed the usual defence response when exposed to a non-feared threatening stimulus, the preattentive processing of the pictures did not reveal autonomic differences between fearful subjects and controls. Mutilation pictures, however, evoked the greatest EMG activity, but only in the fearful group. These data further extend previous research on conscious perception of blood-related stimuli in BII fearful subjects, by showing a failure to recruit autonomic defence responses when blood-related pictures appear outside of conscious awareness.     

Sustained selective intermodal attention modulates processing of language-like stimuli

Intermodal attention (IA) is assumed to allocate limited neural processing resources to input from one specific sensory modality. We investigated effects of sustained IA on the amplitude of a 40-Hz auditory (ASSR) and a 4.3-Hz visual steady-state response (VSSR). To this end, we concurrently presented amplitude-modulated multi-speech babble and a stream of nonsense letter sets to elicit the respective brain responses. Subjects were cued trialwise to selectively attend to one of the streams for several seconds where they had to perform a lexical decision task on occasionally occurring words and pseudowords. Attention to the auditory stream led to greater ASSR amplitudes than attention to the visual stream. Vice versa, the VSSR amplitude was greater when the visual stream was attended. We demonstrate that IA research by means of frequency tagging can be extended to complex stimuli as used in the current study. Furthermore, we show not only that IA selectively modulates processing of concurrent multisensory input but that this modulation occurs during trial-by-trial cueing of IA. The use of frequency tagging may be suitable to study the role of IA in more naturalistic setups that comprise a larger number of multisensory signals.     

Respiratory responses associated with affective processing of film stimuli

We investigated respiratory responses during film clip viewing and their relation to the affective dimensions of valence and arousal. Seventy-six subjects participated in a study using a between groups design. To begin with, all participants viewed an emotionally neutral film clip. Then, they were presented with one out of four emotional film clips: a positive high-arousal, a positive low-arousal, a negative high-arousal and a negative low-arousal clip. Respiration, skin conductance level, heart rate, corrugator activity and affective judgments were measured. Expiratory time was shorter and inspiratory duty cycle, mean expiratory flow and minute ventilation were larger during the high-arousal clips compared to the low-arousal clips. The pleasantness of the stimuli had no influence on any respiratory measure. These findings confirm the importance of arousal in respiratory responding but also evidence differences in comparison to previous studies using visual and auditory stimuli.     

Individual differences in temporal lobe sensory processing of threatening stimuli in the cat.

In Experiment I, neurosensory responses from three limbic areas in the cat brain were recorded when cats of differing defensive temperamental traits were exposed to species characteristic threat. The cats investigated were more or less defensive in response to rats and conspecific threat howls. The behavioral disposition of these cats was stable over retest periods of more than one year. It was found that during visual inspection of rats, more defensive cats displayed greater neural activity in the amygdala and the ventromedial hypothalamus than less defensive cats, who showed no change over baseline. Neurosensory response of the amygdala to conspecific threat howls was also found to be greater in more defensive cats. In contrast, there was no neural response to threat howls in the hypothalamus. Neurosensory response to mice was different from the response to rats and threat howls. Visual inspection of the mouse was associated with a decrease in activity in the amygdalas of more defensive cats. Finally, response of the ventral hippocampus was unspecific, appearing to signal only a change in the stimulus environment. The increase in hypothalamic neural activity in response to rats in more defensive cats appeared to be driven by a potentiated output from the amygdala, since the ratio of hypothalamic to amygdala neurosensory response to rats was greater than one in more defensive cats, but equal to one in less defensive cats. Output of the amygdala was directly investigated using evoked potential techniques in Experiment II. Potentials evoked in the hypothalamus by amygdala stimulation were larger in more defensive cats. Size of the hypothalamic potential was highly correlated with the ratio of hypothalamic to amygdala neurosensory response (ratio response) to rats. Removing the effects of size of the hypothalamic evoked potential from the ratio response by analysis of covariance eliminated the difference between more and less defensive cats in ratio response to rats. The significance of these findings for the physiological bases of defensive response to threat and of temperamental traits are discussed.     

'Prior entry' for pain: attention speeds the perceptual processing of painful stimuli

We investigated whether the perception of simultaneity for pairs of nociceptive and visual stimuli was dependent upon the focus of participants' attention to a particular sensory modality (either pain or vision). Two stimuli (one painful and the other visual) were presented randomly at different stimulus onset asynchronies (SOAs) using the method of constant stimuli. Participants made unspeeded verbal responses as to which stimulus they perceived as having been presented first, or else responded that the two stimuli were presented simultaneously. This temporal discrimination task was repeated under three different attention conditions (blocks): divided attention, attend pain, and attend vision. The results showed that under conditions of divided attention, nociceptive stimuli had to be presented before visual stimuli in order for the two to be perceived as simultaneous. A comparison of the two focused attention conditions revealed that the painful stimulus was perceived as occurring earlier in time (relative to the visual stimulus) when attention was directed toward pain than when it was directed toward vision. These results provide the first empirical demonstration that attention can modulate the temporal perception of painful stimuli.     

Involvement of the retrosplenial cortex in processing multiple conditioned stimuli

Lesions of retrosplenial cortex (RSP) disrupt spatial and contextual learning, suggesting that RSP may have a fundamental role in processing overlapping, or simultaneously presented stimuli. If so, then RSP lesions might also be expected to disrupt learning that requires the concurrent processing of phasic conditioned stimuli. In Experiment 1, rats were trained in a compound feature negative discrimination task in which a tone was presented and immediately followed by food on some trials, while on other trials a visual stimulus was simultaneously presented along with the tone and not reinforced. Normal rats learned to discriminate between the trials but RSP-lesioned rats exhibited low levels of conditioning on both types of trials. Experiment 2 demonstrated that this effect was not simply due to a general inability to form associations, since RSP-lesioned rats exhibited normal responding when the visual stimulus was presented alone and paired with food. These findings support the view that RSP has an important role in learning that involves the processing of simultaneously presented stimuli and have implications for understanding the functional relationship between the hippocampus and RSP.