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Definition; Types a. Overt VS. Covert ? Helmholtz b. Voluntary VS. Reflexive ? the cocktail party effect, dichotic listening Models of Attention = the mechanisms that enable us to process relevant inputs, thoughts, or actions while ignoring irrelevant/ distracting ones. a. Early VS. Late selection i. Early: Broadbent (1958); Posner Cueing Paradigm (endogenous cueing), Spotlight model of attention ii. Late: Deutsch & Deutsch b. Neurobiological evidence that attention can operate both early and late Early:
? higher stage of visual processing when stimulus appears at the cued location
? fMRI evidence that attention modulates low level visual processing (V1 activation) Late: Attention modulates higher level visual processing Both:Attention operates at multiple levels of visual processing hierarchy c. Load theory (Lavie et al, 1995): 2 mechanisms: 1) a passive, perceptual system (bottom-up) 2) an active control mechanism (top-down) Neuropsycological evidence: i. High perceptual load results in better focused attention ii. Opposite effect for high cognitive load
Biased competition model (Desimone & Duncan, 1995) i. Monkey neurophysiology:Chelazzi et al. (1993) - evidence that WM can bias attention at a neural level ii. fMRI (correlational data):Kastner et al (1998) - evidence for competitive interactions in attention Hopfinger et al (2000) - neural activation during cue period provides evidence for a cognitive control network iii. TMS + ERP evidence for a cognitive control network in attention:Morishima et al (2009) - evidence that top-down signals from the PFC modulate the neural processing in the posterior corticles according to the behavioural goal. iv. Neural Mechanisms of Attention: hemispatial neglect Reflexive attention a) Posner cueing paradigm: exogenous cueing b) Inhibition of Return (IoR) Visual search: Feature Integration Theory (Treisman, 1980) Object based attention (rather than space-based attention) Hemispatial neglect a. Spatial (1Rees, 2000) and non-spatial (6Husain, 1997) deficits in neglect seem to be linked (7Robertson, 1998). b. Neglect shows that attention is competitive and 'sticky' (3Rafal, 2002; 6Husain, 1997). c.
- '' -operates on 'internal' as well as 'external' stimuli (the Piazza Demonstration, 4Wokciulik, 2001) d. Unconscious processing may influence our actions (spatial WM cannot account for perseveration) 5Manly, 2002
1. Attention= the ability to focus awareness on a particular object amongst others and subject it to further processing/ act upon it, while ignoring other irrelevant stimuli, thoughts ,and actions. Types of attention: a. COVERT vs. OVERT: Helmholtz's studies revealed covert attention = the idea that we can attend at something without actually looking at it.COVERT= paying attention to one thing while appearing to pay attention to another (the direction to which attention is directed is different from the location at which one is looking) eyes [?] targetOVERT= turning head/eyes to orient attention toward a stimulus b. VOLUNTARY VS. REFLEXIVEVOLUNTARY= intentional, goal-driven ('top-down') by knowledge/ expectations used to guide information processingREFLEXIVE= unintentional, stimulus driven ('bottom-up'), describes the phenomena when sensory event captures our attention Cherry (1953) examined the cocktail party effect = the ability to attend to a single conversation even in a noisy room full of different conversations. He used the dichotic listening task (=the subject wears headphones and sound is presented to only one ear at a time) to determine how well we filter out unattended information. He found that subjects could not detect most properties of the unattended channel (language used, meaning of the message, content), while noticing physical attributes (e.g., human vs. musical instruments) and the gender of the voice.
2. Models of Attention a. Early vs. Late: They differ in where the filtering takes place = the processing bottleneck (=the selection of information due to a limited capacity
- our attentional system can hold only a certain amount of information at any given time)
i) Early selection models: Broadbent (1958) + Posner Cueing Paradigm, Spotlight model of attention According to early selection models, a S does not have to be completely perceptually analyzed before it can be selected for further processing or rejected as irrelevant. Broadbent (1958) proposed such a model of attention to explain data from studies such as that examining the cocktail party effect.
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