Study final Flashcards
(43 cards)
Perception
What is perception
the process by which the nature and meaning of sensory stimuli are recognized and interpreted.
* can be influenced by attention and can occur without conscious awareness
ultimately informs what effectos are used and what behaviour will be generated
Perception
Explain Perception Vs Sensation
Perception != Sensation
* Sensation: detect light stimuli (rods/cones); Perception: determine colou
* Sensation: detect force exerted on skin (cutaneous mechanoeceptors); Perception: determine texture or weight
Perception
What is sensation
The ability to detect and convert stimulus energy into signals that can be reorganized and interpreted by the nervous system
Process of Perception
What are the 3 steps of perception
- Stimulus selection
- Stimulus Organization
- Stimulus interpretation
Process of Perception
Explain the first step in perception
The fist step is stimulus selection which is the decision of what to attend to. It includes selection, attention, top-down control and bottom-up control.
Process of Perception
What is selection
the process by which we attend to some stimuli in our envionment but not others
Process of Perception
What is attention
the ability of the NS to focus on specific sensory info and to disregard other sensory info
Process of Perception
What is top-down control
ability to volitionally direct attention to a particular set or subset of sensory info
Process of Perception
What is bottom-up control
the ability of salient sensory info to break into current intentions and draw attention to that salient info
Process of Perception
Explain the second step of perception
The second step is stimulus organization and it is organize info & integrate various aspects into a single percept. Sensory info about a single stimulus in the environment can arise from multiple senses. Info is first organized within modality specific areas of cortex before being organized within multimodal areas of the cortex
Process of Perception
Explain the third step of perception
the 3rd step is stimulus interpretation and it assigns meaning to stimulus within given context. How you interpret a stimulus is connceted to past experience of having been exposed to that stimulus.
* Past experience stored in ‘database’ called schemas
* when we need a schema, we recall it from long term storage and manipulate it in working memory
Process of Perception
What is a schema
a rule that associate the stimulus with how to act
Process of Perception
What is working memory
a limited capacity cognitive system responsible for temporarily holding info available fo pocessing
Process of Perception
Describe the ways we can engage at each step depending on the task (in increasing complex transformation order). Provide a task example for each wrt touch and vision
- Detection tasks: only perception of presence o absence of stimulus. Touch: monofilament testing; Vision: Peripheral field testing
- Discrimination tasks: require perception of distinguishing characteristics or differences b/w stimuli. Touch: 2-point discrimitation; Vision: Contrast sensitivity
- Identification tasks: Require perception of what stimulus is or how it can be classified. Touch: Steregnosis (identify object w/o vision); Vision: Face recognition
Process of Perception
What is Tactile Agnosia and Astereognosis
Tactile Agnosia: inability to recognize objects by touch
Astereognosis: specific inability to identify size and shape of objects by touch
Touch disorders
Process of Perception
What is Agnosia and prosopagnosia
Agnosia: inability to recognize and identify objects or person
Prosopagnosia: specific inability to recognize faces
Process of Perception
What do bottom-up and top-down processes use to influence/determine perception
Bottom-up processes: detials of sensory input characteristics detemine peception
Top-down processes: influence of prior knowledge, experience and expectation influence perception
both are important for perception
Process of Perception
What is Muiltimodal/multisensory integration
the study of what
The study of how info from the difference sensory modalities may be integrated by the NS. Multimodal integration can be important for perception as well as movement control. The brin naturally wants to integrate info coming from same spatial location and time.
(ex: McGurk effect [Ba vs Fa] or bad lip reading)
Visual Perception
Where does visual perception occur (cortical areas)
- Primary visual cortex: V1
- Visual association areas: V2, V3, V4, V5/MT, V6
Visual Perception
What is the Dual-stream hyposthesis
There are two streams for visual perception:
1. Dorsal stream (where/how): V1 to post. parietal cortex
2. Ventral stream (what): V1 to inferior temporal lobe
Visual Perception
How do we arive at perception in the Vetral stream
(explain the levels of processing)
- Low level processing: different aspects are originally represented separetly in early areas [V1] (eg. orientation, colour, contrast)
- Intermdiate level processing: begin to combine low-level aspects into unified percepts (eg. contour, shape depth)
- High level processing: Combine intermediary representations into a unified percept of entire visual environment [TE, AIT]
Visual Perception
What perception is performed in the dorsal stream
Object motion and direction. Higher level dorsal areas help distinguish our motion from that of objects around us.
Plays critical role in motion processing across multiple modalities (not just vision)
Visual Perception
What is tactile vs visual motion
Tactile: object moved across hand
Visual: Visual stimulus moved across visual field
Visual Perception
What is an Efference copy
an internal copy of an efferent command sent to the spinal cord to effect movement.
