Lead stimulus modality change and the attentional modulation of the acoustic and electrical blink reflex

Two experiments investigated the effects of the sensory modality of the lead and of the blink-eliciting stimulus during lead stimulus modality change on blink modulation at lead intervals of 2500 and 3500 ms. Participants were presented with acoustic, visual, or tactile change stimuli after habituation training with lead stimuli from the same or a different sensory modality. In Experiment 1, latency and magnitude of the acoustic blink were facilitated during a change to acoustic or visual lead stimuli, but not during a change to tactile lead stimuli. After habituation to acoustic lead stimuli, blink magnitude was smaller during tactile change stimuli than during habituation stimuli. The latter finding was replicated in Experiment 2 in which blink was elicited by electrical stimulation of the trigeminal nerve. The consistency of the findings across different combinations of lead stimulus and blink-eliciting stimulus modalities does not support a modality-specific account of attentional blink modulation. Rather, blink modulation during generalized orienting reflects modality non-specific processes, although modulation may not always be found during tactile lead stimuli.     

The effect of stimulus modality and task difficulty on attentional modulation of blink startle

The effects of the sensory modality of the lead stimulus and of task difficulty on attentional modulation of the electrical and acoustic blink reflex were examined. Participants performed a discrimination and counting task with either two acoustic, two visual, or two tactile lead stimuli. In Experiment 1, facilitation of the electrically elicited blink was greater during task-relevant than during task-irrelevant lead stimuli. Increasing task difficulty enhanced magnitude facilitation for acoustic lead stimuli. In Experiment 2, acoustic blink facilitation was greater during task-relevant lead stimuli, but was unaffected by task difficulty. Experiment 3 showed that a further increase in task difficulty did not affect acoustic blink facilitation during visual lead stimuli. The observation that blink reflexes are facilitated by attention in the present task domain is consistent across a range of stimulus modality and task difficulty conditions.     

Attentional blink modulation in a reaction time task: performance feedback,warning stimulus modality,and task difficulty

The present research investigated the effect of performance feedback on the modulation of the acoustic startle reflex in a Go/NoGo reaction time task. Experiment 1 (n = 120) crossed warning stimulus modality (acoustic, visual, and tactile) with the provision of feedback in a between subject design. Provision of performance feedback increased the number of errors committed and reduced reaction time, but did not affect blink modulation significantly. Attentional blink latency and magnitude modulation was larger during acoustic than during visual and larger during visual than during tactile warning stimuli. In comparison to control blinks, latency shortening was significant in all modality conditions whereas magnitude facilitation was not significant during tactile warning stimuli. Experiment 2 (n = 80) employed visual warning stimuli only and crossed the provision of feedback with task difficulty. Feedback and difficulty affected accuracy and reaction time. Whereas blink latency shortening was not affected, blink magnitude modulation was smallest in the Easy/No Feedback and the Difficult/Feedback conditions.     

Attentional blink modulation during sustained and after discrete lead stimuli presented in three sensory modalities

Previous studies found larger attentional modulation of acoustic blinks during task-relevant than during task-irrelevant acoustic or visual, but not tactile, lead stimuli. Moreover, blink modulation was larger overall during acoustic lead stimuli. The present experiment investigated whether these results reflect modality specificity of attentional blink modulation or effects of continuous stimulation. Participants performed a discrimination and counting task with acoustic, visual, or tactile lead stimuli. Stimuli were presented sustained or consisted of two short discrete stimuli. The sustained condition replicated previous results. In the discrete condition, blinks were larger during task-relevant than during task-irrelevant stimuli in all groups regardless of lead stimulus modality. Thus, previous results that seemed consistent with modality-specific accounts of attentional blink modulation reflect effects of continuous stimulus input.     

The effect of emotional and attentional load on attentional startle modulation

The interactive effects of emotion and attention on attentional startle modulation were investigated in two experiments. Participants performed a discrimination and counting task with two visual stimuli during which acoustic eyeblink startle-eliciting probes were presented at long lead intervals. In Experiment 1, this task was combined with aversive Pavlovian conditioning. In Group Attend CS+, the attended stimulus was followed by an aversive unconditional stimulus (US) and the ignored stimulus was presented alone whereas the ignored stimulus was paired with the US in Group Attend CS−. In Experiment 2, a non-aversive reaction time task US replaced the aversive US. Regardless of the conditioning manipulation and consistent with a modality non-specific account of attentional startle modulation, startle magnitude was larger during attended than ignored stimuli in both experiments. Blink latency shortening was differentially affected by the conditioning manipulations suggesting additive effects of conditioning and discrimination and counting task on blink startle.     

Effects of stimulus modality and task condition on blink startle modification and on electrodermal responses

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.     

The effect of warning stimulus modality on blink startle modification in reaction time tasks

The present study investigated the effects of lead stimulus modality on modification of the acoustic startle reflex during three reaction time tasks. In Experiment 1, participants (N = 48) were required to press a button at the offset of one stimulus (task relevant) and to ignore presentations of a second (task irrelevant). Two tones that differed in pitch or two lights served as signal stimuli. Blink startle was elicited during some of the stimuli and during interstimulus intervals. Skin conductance responses were larger during task-relevant stimuli in both groups. Larger blink facilitation during task-relevant stimuli was found only in the group presented with auditory stimuli, whereas larger blink latency shortening during task-relevant stimuli was found in both groups. Experiment 2 (N = 32) used only a task-relevant stimulus. Blink magnitude facilitation was significant only in the group presented with tones, whereas blink latency shortening was significant in both groups. Experiment 3 (N = 80) used a go/nogo task that required participants to press a button if one element of a compound stimulus ended before the second, but not if the asynchrony was reversed. The offset asynchrony was varied between groups as a manipulation of task difficulty. Startle magnitude facilitation was larger during acoustic than during visual stimuli and larger in the easy condition. The present data indicate that startle facilitation in a reaction time task is affected by stimulus modality and by task demands. The effects of the task demands seem to be independent of lead stimulus modality.     

The effect of emotional and attentional processes on blink startle modulation and on electrodermal responses

Emotional accounts of startle modulation predict that startle is facilitated if elicited during aversive foreground stimuli. Attentional accounts hold that startle is enhanced if startle-eliciting stimulus and foreground stimulus are in the same modality. Visual and acoustic foreground stimuli and acoustic startle probes were employed in aversive differential conditioning and in a stimulus discrimination task. Differential conditioning was evident in electrodermal responses and blink latency shortening in both modalities, but effects on magnitude facilitation were found only for visual stimuli. In the discrimination task, skin conductance responses, blink latency shortening, and blink magnitude facilitation were larger during to-be-attended stimuli regardless of stimulus modality. The present results support the notion that attention and emotion can affect blink startle modulation during foreground stimuli.     

Modality-specific attentional startle modulation during continuous performance tasks: a brief time is sufficient

Attentional startle modulation has been found to be modality specific in continuous performance tasks (CPTs) and modality nonspecific in trial-structured tasks. Experiment 1 investigated whether attentional blink modulation in a CPT would change if a trial structure was imposed. Participants performed a visual CPT either continuously (CONT), or during brief periods of time signaled by a change in screen color with stimuli either presented all the time (MIXED) or only during the trial segments (DISC). Contrary to expectation, evidence for modality-specific attentional startle modulation-smaller acoustic startle during targets than during nontargets-was strongest in Groups MIXED and DISC. Experiment 2 confirmed that this pattern of results was present during the first stimulus of the task period in group DISC. This suggests that the continuous nature of a task is not critical in determining the attentional mechanisms engaged.     

Cardiac Orienting and Startle Blink Modification in Novel and Signal Situations

Prior work, has shown that reflex blinking can be facilitated by directing attention to the reflex stimulus. It was assumed that if facilitation were due to sensory enhancement, blinking would also be facilitated by novelty-induced orienting prior to the reflex-eliciting stimulus. The assumption was tested by establishing an expectancy for weak tactile stimulation to be followed by an acoustic reflex stimulus and then introducing, without announcement, trials on which weak acoustic or visual stimuli occurred and were followed by the reflex stimulus. Interspersed control trials of the reflex stimulus alone provided baseline data. Novel trials did produce the expected facilitation of reflex latency and magnitude. Similar effects were obtained when the same stimuli were presented to a different group of subjects with instructions to judge duration of the reflex stimulus on control trials and when warned by the weak acoustic and visual stimuli. In both experiments, blink latency but not magnitude was facilitated by the irrelevant tactile stimuli, thus supporting previous suggestions of a dissociation between these measures of reflex strength. A third group of subjects, receiving identical stimulation, was instructed to attend to the weak acoustic and visual lead stimuli but to perform no task. Attending to the lead stimuli did not produce facilitation of either blink magnitude or latency.     

Effects of Changes in Verbal Stimuli on the Skin Conductance Response Component of the Orienting Response

This paper presents three experiments which were designed to investigate the effects of changes in verbal stimulus meaning on magnitude of the skin conductance response (SCR) component of the orienting response (OR). In Experiments 1 and 2, subjects received 12 visual presentations of a single word stimulus followed by a test trial involving change. The results of Experiment 1 (N = 48) indicated that a test stimulus which constituted change in meaning and taxonomic category induced larger responses than did a change in meaning alone, which in turn induced larger responses than did a control condition of no change. Experiment 2 (N = 64) investigated the effects of both semantic and acoustic changes and the results indicated that only semantic changes resulted in test trial SCRs which were larger than those in the control condition. Experiment 3 (N = 48) investigated the effects on SCR magnitude of within- and between-taxonomic category shifts following habituation training with 4 examples of the category. In this case, only the between-category change resulted in SCRs which were larger than those in the control condition of no change. The results of all three experiments were interpreted as support for Sokolov's (1963) claim that the meaning of verbal stimuli is encoded during habituation. Moreover, the results of Experiment 1 indicate that responsiveness on a change trial is a positive function of the amount of change, while the results of Experiment 3 suggest that when a number of examples of a word class are employed during habituation, the semantic characteristics of that class are encoded.     

Attentional blink reflex modulation in a continuous performance task is modality specific

Four experiments investigated the attentional modulation of acoustic blinks during continuous spatial tracking tasks. Experiment 1 found blink magnitude inhibition in a visual tracking task. Experiment 2 replicated this finding and also found blink latency slowing. Experiment 3 varied the difficulty of the task and found larger blink inhibition in the easy condition. Blink latency slowing did not differ and was significant at both difficulty levels. Experiment 4 employed less difficult visual and acoustic tracking tasks at two levels of task load. Blink magnitude inhibition during the visual and facilitation during the acoustic task was significant during high load in both modality groups. Blink latency was slowed in all visual task conditions and shortened in the difficult acoustic task. These results indicate that attentional blink modulation in a continuous spatial tracking task is modality specific.     

Effects of stimulus preexposure and intermodality change on electrodermal orienting

Previous research has indicated that an intermodality change trial presented after a habituation series elicits larger orienting responses than does the first stimulus of that series. Experiment 1 (N= 48) investigated whether this effect was still present if the change stimulus was not novel but was presented once prior to the habituation series. Two groups of subjects were presented with a series of 24 tones or vibrotactile stimuli. Trial 25 was an intermodality change test trial for half of the subjects in each group (change), whereas the remaining subjects received an additional habituation stimulus (no change). Prior to the habituation trials, each subject was exposed once to the test stimulus used in the change condition. Although response magnitude on the test trial was larger in the change condition than in the no-change condition, test trial response magnitude did not exceed that on the first trial of the habituation series. In Experiment 2 (N= 84), one group was preexposed to the test stimulus, another was preexposed to an experimentally irrelevant stimulus, and a third received no stimulus prior to habituation training. Test trial response magnitude was larger than responses to the first stimulus of habituation in the change group that was not exposed to a stimulus prior to habituation but not in the preexposed groups. Preexposure to a stimulus prior to habituation training abolished the intermodality change effect even when the test stimulus was novel. The present results pose problems for noncomparator theories of habituation and support the notion that anticipatory processes are important in orienting and habituation.     

The "novelty response" in an electric fish: response properties and habituation

The electromotor behavior evoked by novel sensory stimuli in the electrogenic teleost fish Gnathonemus petersii was examined. Novelty responses (NRs) consisted of a transient accelerations of the rate of electric organ discharges following a change in sensory input. NRs were basically similar in nontreated and in immobilized (treated with curare) fish. NRs could be evoked reliably by brief novel stimuli of all four sensory modalities (acoustic, visual, electrical. electrolocation) used in this study. Stimuli of a duration longer than 5 s caused an on- and off-response. A sudden change in the quality of an ongoing sensory stimulus also evoked novelty responses. NR properties depended on the stimulus modality, stimulus intensity, stimulus duration, and on the prior stimulus history. Habituation of several response parameters of the NR (latency, duration, maximal amplitude, response probability) occurred within a series of repetitive stimuli of a given sensory modality. Each modality appeared to habituate separately. Rate of habituation depended on stimulus intensity and on interstimulus interval. A strong disruptive stimulus of another modality lead to dishabituation. The novelty response evoked by stimuli of low or medium intensities resembled an "orienting response" as described by Sokolov.     

Stimulus Omission and Dishabituation of the Electrodermal Orienting Response: The Allocation of Processing Resources

The present research investigated the effects of stimulus omission on electrodermal orienting, dishabituation. and the allocation of processing resources as assessed by reaction time (RT) to a secondary probe stimulus. All experiments employed 33 tone-light or light-tone (S1-S2) pairings, and for experimental groups, S2 was omitted on 4 trials, experiment 1 (N = 24) demonstrated reliable electrodermal responding when S2 was omitted for a trial, and subsequent dishabituation when S2 was then re-presented after SI on the immediately following trial. Experiment 1 (N=96) employed probe RT as the dependent variable. White noise probe stimuli were presented 300 ms or 1300 ms following the omission of S2 and following its onset on re-presentation trials. Reaction time to probes presented during S2 omission was slower in experimental groups than in control groups. Reaction time on S2 re-presentation trials was also slower in experimental groups than in control groups, but only when S3 was a tone. Experiment 3 (N=48) employed auditory and visual probes presented 1300 ms following S2 omission and S2 re-presentation, and measured both electrodermal activity and probe RT, Some evidence of electrodermal omission responding and dishabituation was obtained. Reaction time was again slowed during the omission and re-presentation of S2. regardless of the modality of S2 and regardless of the modality of the probe. The results are interpreted as consistent with an information-processing approach to orienting and habituation in that they indicate that both the omission and re-presentation of an expected stimulus command processing resources.     

Startling secrets: startle eye blink modulation by concealed crime information

We used the startle eye blink paradigm to investigate the processes underlying physiological responding to concealed information. Autonomic responding was measured together with eye blink responses to startle probes presented during mock crime and control pictures. Based upon 'orienting theory', greater startle modulation to crime pictures in comparison to control pictures was expected. The electrodermal, heart rate and respiratory changes in Experiment 1 (n=29) showed enhanced orienting to the crime pictures, but we observed reduced rather than enhanced startle modulation. In Experiment 2 (n=91) and Experiment 3 (n=38), participants either were or were not instructed to inhibit physiological responding in order to test whether inhibition was an explanation for the pattern of startle blink responding. Reduced startle modulation was observed only when participants inhibited physiological responding, confirming the proposed role of inhibition. The data suggest that not only orienting, but also inhibition contributes to physiological responding to concealed information.     

Eye blinks: new indices for the detection of deception

Eyeblink variables were investigated while subjects performed a guilty knowledge test (Experiment 1) and a dual modality attention task (Experiment 2). In both experiments, the temporal distribution of blinks was analyzed using an automatic video based blink analysis system [Matsuo and Fukuda, Jpn. J. Physiol. Psychol. Psychophysiol., 14 (1996), 17]. In experiment 1, the blink rate pattern discriminated between relevant and irrelevant stimuli. In experiment 2, the blink rate peak after the auditory stimulus disappeared during visually attended tasks whereas the blink rate peak after the visual stimulus was significant during auditory attended tasks. It was suggested that eye blinks could be related to the selective attention and that eye blinks could provide an additional index for the detection of deception.     

Effects of allocation of attention on habituation to olfactory and visual food stimuli in children

Responding to food cues may be disrupted by allocating attention to other tasks. We report two experiments examining the effects of allocation of attention on salivary habituation to olfactory plus visual food cues in 8-12-year-old children. In Experiment 1, 42 children were presented with a series of 8 hamburger food stimulus presentations. During each intertrial interval, participants completed a controlled (hard), or automatic (easy) visual memory task, or no task (control). In Experiment 2, 22 children were presented with 10 presentations of a pizza food stimulus and either listened to an audiobook or no audiobook control. Results of Experiment 1 showed group differences in rate of change in salivation (p=0.014). Children in the controlled task did not habituate to repeated food cues, while children in the automatic (p<0.005) or no task (p<0.001) groups decreased responding over time. In Experiment 2, groups differed in the rate of change in salivation (p=0.004). Children in the no audiobook group habituated (p<0.001), while children in the audiobook group did not habituate. Changes in the rate of habituation when attending to non-food stimuli while eating may be a mechanism for increasing energy intake.     

Effects of an Attention-Demanding Task on Amplitude and Habituation of the Electrodermal Orienting Response

Two experiments were designed to investigate the effects of performance of a central task on habituation of the skin conductance response to task-irrelevant stimuli. In Experiment 1 (N=48), subjects performed a visual monitoring task in which stimuli were presented at either 800 or 1000 msec. Half the subjects in each group received task-irrelevant tones of 70dB while the other half did not. The results indicated that task-irrelevant tones elicited responses that were larger than those associated with performance of the monitoring task itself, and that responses were larger and habituation slower in the high demand (800 msec) condition than in the low (1000 msec). In order to distinguish between different explanations of these results, Experiment 2 (N=64) employed the same central task and utilized an unexpected change in the pitch of the task-irrelevant stimulus after 20 habituation trials. The results indicated that although habituation was again slower in the high demand condition than in the low, change trial responsiveness was less in the former than in the latter. The results are discussed in terms of arousal and information-processing accounts of habituation.     

Development of multimodal attention in young infants: modification of the startle reflex by attention

This study examined the effect of attention engagement to compound auditory-visual stimuli on the modification of the startle blink reflex in infants. Infants at 8, 14, 20, or 26 weeks of age were presented with interesting audiovisual stimuli. After stimulus onset, at delays defined by heart rate changes known to be associated with sustained attention or attention disengagement, blink reflexes were elicited by visual or auditory stimuli. Blink amplitude to either visual or auditory stimuli was enhanced when the infants were engaged in attention to the foreground auditory-visual stimuli relative to control trials with no foreground patterns. This enhancement of the blink amplitude increased from 8 to 26 weeks of age. In contrast to selective modality enhancement for single-modality foreground stimuli, these results show that these multimodal stimuli engage both visual and auditory attention systems in this age range.