Join with a free account for more service, or become a member for full access to exclusives and extra support of WorldSupporter >>
Lecture 2 - The eyes (Sensation & perception UU)
Our lens:
- Makes sure that light converges to a single point in our retina
- Does this using accommodation
- Near target: thick lens
- Far target: broad lens
Accommodation is not enough: you also need convergence.
Retina
- We use degrees to measure sizes of things we see visual angle
- Retinal layers:
- In our fovea: there are only cones.
When light hits the rod (or cone) the rhodopsin is broken down and cell hyperpolarizes. So less activity when there is light.
- We have 3 types of cones and 1 rod.
- Rods are more sensitive to cones.
- We don’t see color with rods.
Purkinje shift: the sensitivity to higher wavelengths is less in the dark because rods are insensitive to red (long wavelengths).
Cones are not sensitive to low amounts of light.
Temporal summation: photons reaching a rod add up over time, so fewer are necessary for a response.
What if one of the cone types is missing? Then you are color deficient.
- The L-cone and M-cone missing picture looks quite the same, cause they have overlap in their wavelengths.
There is always photon noise.
So:
- Light of the retina is noisy
- The density of receptors determines spatial acuity
- Type of receptor determines temporal acuity/sensitivity
- Stimulus-point on the retina has a spread with gradual slope towards un-stimulated area
We do not perceive light, we perceive changes in light (intensity) across space and/or time.
Horizontal cells:
- Create a sharper picture
Amacrine cells (not very important for exam)
Bipolar cells (important):
- On center (inverting)
- Off center (non-inverting)
Center-surround organisation
Three types of ganglion cells
- M cells (large receptive field)
- Have on and off cells and different cells for different colors
- Slow temporal response
- P cells (small receptive field)
- Fast
- L cells
- No center surround because we only have a few cones
Center-surround is important!
Questions? Let me know in the contribution section!
Follow me for more summaries / lecture notes!
Access:
Public
Contributions: posts
Help other WorldSupporters with additions, improvements and tips
Spotlight: topics
Check how to use summaries on WorldSupporter.org
Online access to all summaries, study notes en practice exams
- Check out: Register with JoHo WorldSupporter: starting page (EN)
- Check out: Aanmelden bij JoHo WorldSupporter - startpagina (NL)
How and why would you use WorldSupporter.org for your summaries and study assistance?
- For free use of many of the summaries and study aids provided or collected by your fellow students.
- For free use of many of the lecture and study group notes, exam questions and practice questions.
- For use of all exclusive summaries and study assistance for those who are member with JoHo WorldSupporter with online access
- For compiling your own materials and contributions with relevant study help
- For sharing and finding relevant and interesting summaries, documents, notes, blogs, tips, videos, discussions, activities, recipes, side jobs and more.
Using and finding summaries, study notes and practice exams on JoHo WorldSupporter
There are several ways to navigate the large amount of summaries, study notes en practice exams on JoHo WorldSupporter.
- Use the menu above every page to go to one of the main starting pages
- Starting pages: for some fields of study and some university curricula editors have created (start) magazines where customised selections of summaries are put together to smoothen navigation. When you have found a magazine of your likings, add that page to your favorites so you can easily go to that starting point directly from your profile during future visits. Below you will find some start magazines per field of study
- Use the topics and taxonomy terms
- The topics and taxonomy of the study and working fields gives you insight in the amount of summaries that are tagged by authors on specific subjects. This type of navigation can help find summaries that you could have missed when just using the search tools. Tags are organised per field of study and per study institution. Note: not all content is tagged thoroughly, so when this approach doesn't give the results you were looking for, please check the search tool as back up
- Check or follow your (study) organizations:
- by checking or using your study organizations you are likely to discover all relevant study materials.
- this option is only available trough partner organizations
- Check or follow authors or other WorldSupporters
- by following individual users, authors you are likely to discover more relevant study materials.
- Use the Search tools
- 'Quick & Easy'- not very elegant but the fastest way to find a specific summary of a book or study assistance with a specific course or subject.
- The search tool is also available at the bottom of most pages
Do you want to share your summaries with JoHo WorldSupporter and its visitors?
- Check out: Why and how to add a WorldSupporter contributions
- JoHo members: JoHo WorldSupporter members can share content directly and have access to all content: Join JoHo and become a JoHo member
- Non-members: When you are not a member you do not have full access, but if you want to share your own content with others you can fill out the contact form
Quicklinks to fields of study for summaries and study assistance
Field of study
- All studies for summaries, study assistance and working fields
- Communication & Media sciences
- Corporate & Organizational Sciences
- Cultural Studies & Humanities
- Economy & Economical sciences
- Education & Pedagogic Sciences
- Health & Medical Sciences
- IT & Exact sciences
- Law & Justice
- Nature & Environmental Sciences
- Psychology & Behavioral Sciences
- Public Administration & Social Sciences
- Science & Research
- Technical Sciences
Follow the author: JuliaV
Work for WorldSupporter
JoHo can really use your help! Check out the various student jobs here that match your studies, improve your competencies, strengthen your CV and contribute to a more tolerant world
Statistics
| 2261 |
Add new contribution