2111 Attention L1.pptx

Selective Attention 1 (PS2111) Dr. Doug Barrett e-mail:[email protected] Selective Attention “Everyone knows what attention is. It is the taking of possession by the mind, in clear and vivid form, of one of what seem several simultaneously possible objects or trains of thought” (William James, 1890). P...

Selective Attention 1 (PS2111) Dr. Doug Barrett e-mail:[email protected] Selective Attention “Everyone knows what attention is. It is the taking of possession by the mind, in clear and vivid form, of one of what seem several simultaneously possible objects or trains of thought” (William James, 1890). PS2111 Selective Attention What is selection? – Prioritisation of a subset of information Why do we need selection? – Brain receives information from multiple sensory systems – Not all of the information is relevant at any one time – Physiological limits imposed by effector systems (i.e., eyes & hands) PS2111 Selective Attention Why do we need selection (continued)? – Capacity limits associated with neural function & metabolism Visual selective attention – Physiology of visual system imposes constraints on the type and amount of information observers obtain from the environment (scene) PS2111 PS2111 Gradient of visual acuity determines the spatial resolution of information sampled in a single fixation PS2111 Eye movements: overt attention How do we decide where to fixate? Random sequence? Guided sequence? Selective Attention Covert attention Prioritises areas (objects) for action (e.g., eye movements) Prioritises information for analyses and retention PS2111 Target = PS2111 Target = PS2111 or Selective Attention Post-perceptual processes Working memory Capacity limited temporal store Verbal STM (7 ± 2) Visual WM ( uncued baseline – Spatial acuity at uncued locations Attention and Spatial Acuity Attention and Spatial Acuity Attention and Spatial Acuity Attention and Spatial Acuity Attention and Spatial Acuity Attention and Spatial Acuity Attention and Spatial Acuity Object at cued location VALID Gap at the top or bottom? Attention and Spatial Acuity INVALID Gap at the top or bottom? Object at uncued location Attention and Spatial Acuity Size of the gap Observers require to obtain 75% accuracy Attention and Spatial Acuity Spatial acuity at cued location was significantly higher than uncued baseline Concomitant decrease in acuity at uncued location Covert attention mediates changes in observer’s spatial acuity in the absence of eye movements PS2111 Attention and Signal-toNoise Previous study presented stimuli very fast to make discrimination difficult Objects outside the lab are often accompanied by noise: – Occluding objects in visual scenes – Competing voices in auditory scenes Dosher & Lu investigated whether attention includes a “noise-exclusion” mechanism PS2111 Attention and Signal-toNoise Target contrast External noise Exogenous cue (arrow) Target contrast Observers require to obtain 62.5% accuracy IV V Attention and Signal-toNoise Discriminability of the target at cued locations was higher than at uncued locations The affect of cueing was more pronounced in displays containing high levels of external noise Selective attention increases detection at cued location by Signa 1 1 increasing the signal-to-noise ratio l PS2111 Noise 1.5 Attention and Signal-toNoise Unattended Attended Target contrast External noise Auditory Selective Attention Spence & Driver (1997; 1994) investigated benefits of auditory spatial attention using an “orthogonal” cueing paradigm PS2111 (i) Spatial (up or down?) (i) Predictive (endogenous) (ii) Non-predictive (exogenous) (ii) Non-spatial (high or low?) Auditory Selective Attention Valid < invalid Filled symbols = valid cue Solid lines = spatial Solid lines = valid cue Auditory Selective Attention Eramudugolla et al. (2005). Feature-based selection and auditory working memory Auditory Selective Attention Selective auditory attention – Increases spatial acuity of auditory localisation – Increases acuity of non-spatial judgements (pitch) – Protects selected items from degradation in auditory working memory Exogenous and endogenous cues PS2111 produce similar benefits but have Summary Selective attention is a set of processes that protect capacity-limited perceptual and post-perceptual resources Shifts of spatial attention can be triggered – Exogenously – endogenously Covert spatial attention – Increases spatial resolution – Increases signal-to-noise ratio – Combines sensory information across modalities PS2111 So what? – from lab to life Signal-to-noise in visual perception Can you think of other examples? PS2111 – In audition? – How might age affect signal-to-noise in sensory systems? Further reading: Any cognitive text book that includes a chapter on attention References in the lecture: 1. Muller, H.H., & Rabbitt, P.M.A. (1989). Journal of Experimental Psychology: Human Perception and Performance, 58(3): 193-198. 2. Montagna, B., et al. (2009). Vision Research, 49(7): 735-745. 3. Dosher, B.A., & Lu, Z-L (2000). Psychological Science, 11(2): 139146. 4. Spence, C., & Driver, J. (1998). Perception and Psychophysics, 60: 125-139. 5. Barrett, D.J.K., & Krumbholz, K. (2012). Experimental Brain Research, 222: 11-20. PS2111