w11 VSE Vision and Attention Flashcards
(22 cards)
How does human vision differ from photography?
human vision is an active, dynamic process where the brain creates short-lived models of the external world based on current visual needs, goals and expectations, unlike photography which is passive
What is the difference between ‘bottom-up’ and ‘top-down’ processing in visual perception?
- bottom-up processing: refers to processing sensory input e.g. light and shapes
- top-down processing involves using knowledge, expectation and context to interpret sensory input
why is attention imp for visual perception??
attention helps the brain prioritise and process relevant details while filtering out irrelevant info, necessary as the brain has limited capacity to process all the visual input at once
voluntary attention?
the conscious decision to focus on a specific object or location.
involuntary attention?
the automatic shift of attention towards sudden or noticeable events, often in the peripheral vision.
Covert attention??
focusing on an object or area without moving the eyes.
overt attention?
shifting the eyes (saccades) to focus on an object, accompanied by foveation.
What is the purpose of saccades in visual exploration?
Saccades are rapid, jerky eye movements that help scan a scene or gather information for a specific task. They enable us to explore our environment and focus on areas of interest.
What are smooth pursuit movements and why are they important?
Smooth pursuit eye movements allow us to track moving objects and keep them on the fovea, minimising motion blur.
What are micro-saccades and their role in fixation?
Micro-saccades are small eye movements during fixation that prevent visual fading by maintaining visual perception through continuous retinal activity.
What is Feature Integration Theory by Anne Treisman?
Feature Integration Theory suggests that visual features (like color, shape, and motion) are processed separately in the brain and then “bound” together by attention to form a coherent perception of an object.
intentional blindness???
occurs when we fail to perceive objects in our field of view due to a lack of attention.
change blindness???
happens when large changes in a scene are not noticed because attention is not focused on the altered elements.
What is the neural basis of attention in visual perception?
How our brain works when we pay attention to smth: when focusing on smth the brain boosts activity in areas that help process that specific thing, reducing activity in areas not related, this helps the brain prepares to deal w/ the imp info ignoring anything irrelevant
How do attentional shifts affect brain activity according to Yamagishi et al. (2005)?
Attentional shifts are when you focus on something specific, when you shift your attention, the brain lowers alpha activity , allowing it to focus more on the things you’re paying attention to. This helps your brain get ready for the new visual information that’s coming in, particularly in the calcarine cortex (the part of the brain that helps with vision).
What is hemifield neglect and what causes it?
Hemifield neglect occurs when damage to the right parietal cortex causes a person to ignore one half of their visual field, often due to stroke or brain lesions.
What is blindsight and what does it demonstrate about visual perception?
Blindsight occurs when a person is blind in part of their visual field but can still respond to visual stimuli there. It demonstrates that awareness and perception can be segregated.
What is the effect of split-brain surgery on attention?
Split-brain surgery, which severs the corpus callosum, can cause subtle attentional deficits where patients may perform tasks without conscious awareness due to the lack of communication between hemispheres.
How does change blindness affect visual perception in real-world situations?
Change blindness highlights that we often fail to notice large changes in our environment unless we direct attention to those aspects, affecting tasks like eyewitness testimony and driving.
What is the role of the parietal lobe in attention
The parietal lobe is crucial for spatial attention and helps direct focus to relevant stimuli. Lesions in this area can lead to attentional deficits like hemifield neglect.
How does neural coherence relate to attention in visual performance?
Neural coherence refers to how well the brain’s electrical signals are synchronised when you focus on something. When there’s higher neural coherence, especially in the 2-10 Hz frequency range, it means your brain is better at focusing and processing relevant information. It shows that your brain is actively enhancing the signals that matter
Describe three types of eye movements.
Vergence:
A slow response driven by binocular image differences.
Helps achieve binocular fixation at different distances.
Saccades:
Rapid, jerky eye movements while scanning or reading.
Occur about 3-4 times per second, mostly unnoticed.
Vision remains stable, despite the jumps.
Can be voluntarily controlled; scanning patterns depend on the task.
Helps fovea acquire fine detail at points of interest.
In reading, each jump covers 7-9 letters, with each fixation lasting 200-300 ms.
Smooth Pursuit:
Tracks moving objects to keep them on the fovea and reduce motion blur.
Can track both visual and sound-moving targets.
Doesn’t work if there’s nothing to follow.
