Attentional Studies PDF

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Attentional Studies Measuring/Quantifying Attention   

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Posner et al., 1980 Spatial cueing task Participants were asked to determine whether the go signal was on the left or right side of the computer screen. 75% of trials, a cue (flash) was given just before the go signal popped up. Sometimes the cue would be on the same side as the go signal, and sometimes it was on the contralateral side. Participants’ performance was increased when the cue was presented to the same visual field as the stimuli. This implies cues are important to divert spatial attention to one place, allowing participants to easily spot the stimuli. To quantify this information in order to measure attention, reaction times for each trial was recorded. Reaction times when the stimulus followed the cue were lower. Reaction times for expected locations were significantly faster than those for unexpected and neutral conditions.

M Dichotic listening task Participants wore headphones and were presented two separate pieces of information. They were asked to shadow one particular piece of information and report it back to the researcher, this would become the attended channel. The other information would go through the unattended or ignored channel. M believed that participants would be able to recall information from the attended channel, and have blocked information from the unattended channel, therefore not remembering any of that information. – which is what the study found. ERP – signal averaging found attended channel signals were significantly higher than unattended channels.

Voluntary Attention

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Hopfinger et al., 2000 Selective attention, attentional control fMRI BOLD signal Found contralateral enhancement of BOLD signal when attended – in V1, V2, VP and V4 areas of the visual cortex. Intraparietal sulcus – in response to cue stimuli, not to target stimuli Frontal eye fields, superior frontal gyrus – activity processing the stimuli Posterior parietal lobes – activity in target stimuli

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Given the limited temporal resolution of fMRI, however, it has been difficult to determine whether these attention-related increases in activity represent an enhancement of early sensory-evoked responses, a delayed modulation of activity due to feedback from higher areas, or a sustained increase in activity associated with the spatial focusing of attention. The time course of these spatial attention effects in humans has been clarified by recordings of ERPs

La Berge (1983) Asked participants to focus on either the central letter or the whole word. If they were asked to focus on the central letter, they had higher recall (therefore higher attention) for this letter, rather than the whole word. Top down attention, endogenous, voluntary

Treisman (1988) Visual search Participants were asked to detect the presence of absence of a letter (F), and ignore surrounding, distracting letters (E and T) Top down, endogenously driven attention by detecting a certain letter

Reflexive Attention

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Hopfinger and Mangun., (1998, 2001) Reflexive attention, attention is captured by an object undergoing salient change Attention-capturing cues initially result in faster and more accurate responses to stimuli at the captured location, but at slightly longer intervals between the capturing event and subsequent target, subjects are slower to respond to stimuli at the attended location. This phenomenon has been termed inhibition of return (IOR0 as attention appears to be inhibited from returning to the location that it was previously engaged at Posner spatial cueing task for reflexive attention – cue is a flash of light At short cue-to-target intervals, Hopfinger and colleagues found that these nonpredictive abrupt reflexive cues result in enhanced cortical visual processing for subsequent stimuli that occur at the cued location relative to stimuli at uncued locations. – specifically P1. Furthermore, the enhancement of the P1 component occurred whether subjects were performing a difficult discrimination task (Hopfinger & Mangun, 1998), were engaged in a simple detection task (Hopfinger & Mangun, 2001), or were simply viewing task-irrelevant stimuli (Hopfinger et al., 2000b). This pattern of results, combined with the fact that the cue stimuli were completely

nonpredictive of target location or target type, suggests that the P1 effect here is due to truly reflexive mechanisms Spatial Attention  

Activation in the lateral geniculate nuclei and visual cortex for attended stimuli Evidence from fMRI

Feature-Based Attention   

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Activation in the feature-specific area of the visual cortex for attended stimuli Evidence from fMRI Visual search paradigm (shapes that are different colours e.g. blue and red) Participants were asked to identifying blue shapes. Conditions (one blue stimuli, and multiple blue stimuli) Quantifying by time taken to find the stimulus Illusory conjunctions (attention could not take place due to such a brief period of time looking at stimuli, participants may recall they saw a red H when in fact they saw a blue H and red E) Patients with parietal damage often show a higher rate of illusory conjunctions

Object-Based Attention   

Activation in the object-specific area of the visual cortex e.g. fusiform face area for attended to faces or parahippocampal area for processing houses Evidence from fMRI Even though they are in the same special area, they can attend to a specific object depending on the goals (top down)...