Sakinah Alhadad (2011). ATTENTIONAL MODULATION OF THE STARTLE EYEBLINK REFLEX: THE ROLE OF STIMULUS MODALITY PhD Thesis, School of Psychology, The University of Queensland.

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Author Sakinah Alhadad
School, Centre or Institute School of Psychology
Institution The University of Queensland
Publication date 2011-03
Thesis type PhD Thesis
Supervisor Professor Ottmar V. Lipp
Professor Roger Remington
Dr Helena Purkis
Total pages 254
Total colour pages 5
Total black and white pages 249
Subjects 17 Psychology and Cognitive Sciences
Abstract/Summary Modality specificity or non-specificity of attentional startle modulation can reflect the amount of processing required prior to stimulus selection and may be useful to delineate the attentional requirements of a particular situation. The effect of attention on startle was initially believed to be modality specific, i.e., startle modulation patterns were said to depend on the sensory modalities of the attended and the reflex-eliciting stimuli. This viewpoint was challenged by more recent evidence for modality nonspecific attentional startle modulation in various experimental paradigms. Here, startle was enhanced following attended stimuli regardless of their sensory modality. The aim of this thesis was to investigate task characteristics which determine whether attentional startle modulation is modality specific or non-specific. Experiment 1 investigated whether modality specific attentional startle modulation occurred across a short digit stream presentation in a continuous performance task (CPT). Modality specific attentional startle modulation emerged within a modified CPT, even with an imposed trial structure, suggesting that the trial structure may not be a crucial factor. Experiment 2 explored whether modality specific attentional startle modulation can be found if the task consists of digit pairs rather than streams. Modality specific effects were found in a 6-digit task, but not in a 2-digit task, indicating that continued processing may be required for the emergence of attentional startle modulation. Experiment 3a assessed the effect of cue-target intervals on attentional startle modulation in a differential reaction time task. Observations of trends towards modality specific attentional startle modulation in task blocks with short cue-target intervals and modality nonspecificity in task blocks with long cue-target intervals suggested a role of the different interstimulus intervals (ISIs) used in these tasks. However, awareness of the cue-target relationship during this study was poor. Experiment 3b re-examined the effect of ISI with the provision of instructions to increase contingency awareness. This manipulation obliterated the effects found in Experiment 3a. On the basis of both studies, it was postulated that uncertainty within the task may interact with ISI to affect attentional startle modulation. Experiment 4 investigated the effect of task uncertainty by manipulating cue validity. Startles were smaller following targets than non-targets only in the 100% task block at a lead interval of 1,200 ms. Experiment 5 examined the effects of uncertainty on startle modulation by distributing the cue validity conditions in short alternating task segments within each block rather than across blocks. Startles were smaller following targets than following non-targets in both 50% and
Keyword startle eyeblink reflex
Stimulus Modality
Reaction Time Task
Temporal uncertainty
Cue validity
continuous performance task
foreperiod paradigm
Additional Notes Colour pages: page 94, 99, 111, 123, 133

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Created: Mon, 19 Sep 2011, 14:33:13 EST by Ms Sakinah Alhadad on behalf of Library - Information Access Service