Biomedical subjects

David L Neumann

Publications and source records attributed to David L Neumann.

10 recordsLinked to original sources

PubMed2006

Changes in implicit associations do not occur simultaneously to Pavlovian conditioning of physiological anxiety responses.

Previous research shows that an 'angry face' conditioned stimulus will elicit conditioned skin conductance responses (SCR) after a small number of trials pairing it with a mild electric shock. Such conditioning occurs even with masked presentations of the facial stimulus. Furthermore, the Implicit Association Test (IAT) has been demonstrated to be sensitive to the presence of information processing biases seen in specific phobias. We examined the ability of the IAT to detect changes in implicit associations that arise from pairing one facial image (CS+) with a mild electro-tactile stimulation whereas a second facial image (CS-) was presented alone. Participants (N=117) were assigned to one of four groups: a group that received no shocks with unmasked presentation of the facial images; a group that received no shocks with masked presentation; a group with shocks delivered simultaneously to the masked presentation of the CS+; and a group that received shocks simultaneous to unmasked CS+ presentation. Learning was assessed through both SCR and the IAT. Results showed that while it was possible to condition a SCR to the CS+, this learning was not detectable using the IAT. Implications of the discrepancies in the outcome measures are discussed.

Analysis of Variance↗

PubMed2006

Prepulse inhibition of the startle blink reflex is modulated during a memory task requiring prepulses to be encoded for later report.

Prepulse inhibition (PPI) of the startle blink reflex in humans can be modulated by selective attention to the prepulse. The present experiment used a memory task to determine whether the encoding of information for later report can modulate PPI. Participants were briefly presented with a display of one or three letters followed by a pattern mask and asked to make a delayed report of the letter(s) shown. Memory recall was better in the 1-letter condition than in the 3-letter condition. Prepulse inhibition was greater in the 3-letter condition than in the 1-letter condition at lead intervals of 120 and 240 ms following the onset of the letter display. Blink modulation did not differ between the letter conditions at lead intervals of 120, 240, 360, or 2600 ms following the mask, ruling out other explanations (e.g., rehearsal) for the earlier difference in PPI. The results suggest that the short-term consolidation of memory, and possibly any cognitive process that requires access to a theoretical limited capacity central processing mechanism modulates PPI.

Adolescent↗

PubMed2006

The use of an unpleasant sound as an unconditional stimulus in a human aversive Pavlovian conditioning procedure.

Ethical considerations can limit the use of traditional unconditional stimuli (US), such as electric shock and loud tones, when used in a human aversive Pavlovian conditioning procedure. The risk of the US causing pain or excessive anxiety is a particular concern when testing sensitive populations such as children, the elderly, and those with psychological or neurodevelopmental disorders. Two experiments used a differential conditioning procedure to determine whether an unpleasant sound (metal scraping on slate) could support the acquisition and extinction of conditioned responses to the same extent as either electric shock or a 100 dB(A) tone US. Experiment 1 (N=48) demonstrated equivalent or superior conditioning effects for the signal-based learning measures of US expectancy, skin conductance responses, and heart rate. Experiment 2 (N=57) yielded similar outcomes in the affective-based learning measures of startle blink modulation and pleasantness ratings. The results support the use of an unpleasant sound as a US in human Pavlovian conditioning experiments.

Acoustic Stimulation↗

PubMed2006

Conducting extinction in multiple contexts does not necessarily attenuate the renewal of shock expectancy in a fear-conditioning procedure with humans.

The renewal of Pavlovian-conditioned responses may provide a model for the relapse of fear following extinction-based treatments for anxiety disorders. Renewal can be observed if conditional stimulus (CS) and unconditional stimulus (US) pairings are given in one context, extinction trials of CS presentations in a second context, prior to test trials of CS presentations in the original acquisition context (ABA renewal). We examined ABA renewal in humans by using a fear-conditioning procedure with an unpleasant shock US. A renewal of rated shock expectancy was demonstrated with this procedure. Conducting extinction treatment in multiple contexts was expected to attenuate the renewal effect. However, the renewal of shock expectancy persisted when extinction treatment was given across three or five different contexts. With the current renewal design, learning task, and measure of conditioned behaviour, extinction treatment does not appear to readily generalise to the test context. The use of multiple extinction treatments in a clinical setting may not necessarily reduce the likelihood of relapse via a renewal effect.

Adolescent↗

PubMed2004

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.

Acoustic Stimulation↗

PubMed2004

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.

Acoustic Stimulation↗

PubMed2004

The effects of lead stimulus and reflex stimulus modality on modulation of the blink reflex at very short, short, and long lead intervals.

The blink reflex is modulated if a weak lead stimulus precedes the blink-eliciting stimulus. In two experiments, we examined the effects of the sensory modality of the lead and blink-eliciting stimuli on blink modulation. Acoustic, visual, or tactile lead stimuli were followed by an acoustic (Experiment 1) or an electrotactile (Experiment 2) blink-eliciting stimulus at lead intervals of -30, 0, 30, 60, 120, 240, 360, and 4,500 msec. The inhibition of blink magnitude at the short (60- to 360-msec) lead intervals and the facilitation of blink magnitude at the long (4,500-msec) lead interval observed for each lead stimulus modality was relatively unaffected by the blink-eliciting stimulus modality. The facilitation of blink magnitude at the very short (-30- to 30-msec) lead intervals was dependent on the combination of the lead and the blink-eliciting stimulus modalities. Modality specific and nonspecific processes operate at different levels of perceptual processing.

Acoustic Stimulation↗

PubMed2003

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.

Acoustics↗

PubMed2003

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.

Acoustic Stimulation↗

PubMed2002

Effect of varying levels of mental workload on startle eyeblink modulation.

Previous research using punctuate reaction time and counting tasks has found that the startle eyeblink reflex is sensitive to attentional demands. The present experiment explored whether startle eyeblink is also modulated during a complex continuous task and is sensitive to different levels of mental workload. Participants (N = 14) performed a visual horizontal tracking task either alone (single-task condition) or in combination with a visual gauge monitoring task (multiple-task condition) for three minutes. On some task trials, the startle eyeblink reflex was elicited by a noise burst. Results showed that startle eyeblink was attenuated during both tasks and that the attenuation was greater during the multiple-task condition than during the single-task condition. Subjective ratings, endogenous eyeblink rate, heart period, and heart period variability provided convergent validity of the workload manipulations. The findings suggest that the startle eyeblink is sensitive to the workload demands associated with a continuous visual task. The application of startle eyeblink modulation as a workload metric and the possibility that it may be diagnostic of workload demands in different stimulus modalities is discussed.

Adult↗