Hubel DH, Wiesel TN. Brain Mechanisms of Vision. Scientific American. 1979 Sep; 241(3):150-62
Summary:
The brain's primary visual cortex processes images in a modular, distorted way. The rods and cones in the eyes send messages from the retina to the geniculate cells in the brain, which then relay the message to the visual cortex. These geniculate cells are in a layer called Layer IV, are unsophisticated, and receive the bulk of the visual input.
Cells outside of layer IV have "orientation specificity", where a bar of light falling in a certain orientation will activate some cells and have no affect on others. The response for each cell appears to be around 10-20 degrees, at which point the response is lessened or abolished.
At the time (1979), there was no evidence to support that the orientation specific cells had anything to do with visual perception.
As electric signals moved into more complex layers of the visual cortex, some patterns emerged. Cells close to one another often have the same optimal stimulus orientation. Changes in orientation happen in small increments, such as 25-50 micrometers between cell groups mapping to a change of 10 degrees with varying direction reversals.
Discussion:
Really interesting information on how the structure and hierarchy of the primary visual cortex. Although the orientation information did not prove that the brain recognizes shapes using features such as line orientations, other papers citing this one might. I'll have to find some...
Thursday, June 11, 2009
Unseen and Unaware: Implications of Recent Research on Failures of Visual Awareness for Human–Computer Interface Design
Varakin, D. A., Levin, D. T., and Fidler, R. 2004. Unseen and unaware: implications of recent research on failures of visual awareness for human-computer interface design. Hum.-Comput. Interact. 19, 4 (Dec. 2004), 389-422. DOI= http://dx.doi.org/10.1207/s15327051hci1904_9
Summary:
The authors mention some research on inattentional blindness and change blindness and provide anecdotal evidence of their usage in computer interfaces
Summary:
The authors mention some research on inattentional blindness and change blindness and provide anecdotal evidence of their usage in computer interfaces
- Inattentional Blindness - user is unaware of a change occurring within the same field of view
- Change Blindess - user is unaware of a change occurring across multiple views
Change blindness: past, present, and future
Daniel J. Simons, Ronald A. Rensink, Change blindness: past, present, and future, Trends in Cognitive Sciences, Volume 9, Issue 1, January 2005, Pages 16-20, ISSN 1364-6613, DOI: 10.1016/j.tics.2004.11.006. (http://www.sciencedirect.com/science/article/B6VH9-4DXTHVD-2/2/d3451247e53c70b0b390450a275a475a)
Summary:
The authors provide an overview of change blindness understanding, such as how research has shown that change blindness occurs often during eye movement or when a user's attention wanes.
The main contribution of the paper is the idea that change blindness research does not confirm the thought that visual representations of a scene are 'sparse'. The authors propose four requirements for a change blindness to reaffirm the idea of sparse representations:
The paper's final thoughts on how a representation are stored do not concern me. Instead, this paper has a wide bibliography of change blindness research that should help me to look for related work.
Summary:
The authors provide an overview of change blindness understanding, such as how research has shown that change blindness occurs often during eye movement or when a user's attention wanes.
The main contribution of the paper is the idea that change blindness research does not confirm the thought that visual representations of a scene are 'sparse'. The authors propose four requirements for a change blindness to reaffirm the idea of sparse representations:
- Evidence must eliminate the possibility that detailed visual representations exist by fade from memory before the representations can be compared with others to perceive changes
- Evidence must eliminate the possibility that detailed visual representations exist, but in a different visual processing section (of the brain?) that cannot compare with the currently viewed representation for change detection
- Evidence must eliminate the possibility that any stored detailed representation is in a format that cannot be compared with another representation
- Evidence must eliminate the possibility that both the stored detailed representation and the viewed representation can be compared, but are not for some reason
The paper's final thoughts on how a representation are stored do not concern me. Instead, this paper has a wide bibliography of change blindness research that should help me to look for related work.
Sunday, February 22, 2009
CogSketch: Open-domain sketch understanding for cognitive science research and for education
Summary
CogSketch presents a sketch recognition system wrapped in psychological syntax. Users draw single stroke glyphs that can be containment glyphs (symbols) or connection glyphs (relationships). Glyphs are recognized through a focused knowledge base of information that can be specified by the user. Inter-glyph relationships are computed using RCC-8.
On the interface side, the system contains layers that have modes.
Lastly, CogSketch has simulations that can be conducted. The two simulations are analogies (A is to B as C is to ?) and spatial language learning (inside, above, below, etc.).
CogSketch presents a sketch recognition system wrapped in psychological syntax. Users draw single stroke glyphs that can be containment glyphs (symbols) or connection glyphs (relationships). Glyphs are recognized through a focused knowledge base of information that can be specified by the user. Inter-glyph relationships are computed using RCC-8.
On the interface side, the system contains layers that have modes.
Lastly, CogSketch has simulations that can be conducted. The two simulations are analogies (A is to B as C is to ?) and spatial language learning (inside, above, below, etc.).
Do Background Images Improve “Draw a Secret” Graphical Passwords?
Dunphy, P. and Yan, J. 2007. Do background images improve "draw a secret" graphical passwords?. In Proceedings of the 14th ACM Conference on Computer and Communications Security (Alexandria, Virginia, USA, October 28 - 31, 2007). CCS '07. ACM, New York, NY, 36-47.
Summary
The authors use DAS passwords in conjunction with background images in order to improve the complexity of the passwords without harming user recall. A user would typically choose a small portion of an image to draw on, which could increase the complexity of the password if the image itself was complex.
The paper contains great user studies focusing on the recall of passwords, the complexity of images, what images users chose to draw on, and what recall errors occurred.
Discussion
This is another DAS paper, and, like the previously blogged one, shows how much room the graphical password field has to grow. The studies in this paper were phenomenally thorough, and if we ever start a sketching passwords project this is the paper we should all read.
Summary
The authors use DAS passwords in conjunction with background images in order to improve the complexity of the passwords without harming user recall. A user would typically choose a small portion of an image to draw on, which could increase the complexity of the password if the image itself was complex.
The paper contains great user studies focusing on the recall of passwords, the complexity of images, what images users chose to draw on, and what recall errors occurred.
Discussion
This is another DAS paper, and, like the previously blogged one, shows how much room the graphical password field has to grow. The studies in this paper were phenomenally thorough, and if we ever start a sketching passwords project this is the paper we should all read.
Graphical Passwords & Qualitative Spatial Relations
Lin, D., Dunphy, P., Olivier, P., and Yan, J. 2007. Graphical passwords & qualitative spatial relations. In Proceedings of the 3rd Symposium on Usable Privacy and Security (Pittsburgh, Pennsylvania, July 18 - 20, 2007). SOUPS '07, vol. 229. ACM, New York, NY, 161-162.
Summary
The authors modify the Draw-a-Secret (DAS) scheme where users draw a graphical password in a grid so that the "looking over the shoulder" phenomenon could be reduced. A DAS password is a simple encoding of a drawn stroke using a grid and directions, such as up, right, up.
The extended abstract presents a Qualitative Draw-a-Secret (QDAS) scheme that changes DAS by first assigning a number to each grid. Then, the grid itself varies based on the direction changes of the stroke. The grid changes based on cell height and width.
Discussion
Although this extended abstract wasn't too informative, it did give me some thoughts about how we could use sketch recognition techniques to improve upon drawn passwords.
Summary
The authors modify the Draw-a-Secret (DAS) scheme where users draw a graphical password in a grid so that the "looking over the shoulder" phenomenon could be reduced. A DAS password is a simple encoding of a drawn stroke using a grid and directions, such as up, right, up.
The extended abstract presents a Qualitative Draw-a-Secret (QDAS) scheme that changes DAS by first assigning a number to each grid. Then, the grid itself varies based on the direction changes of the stroke. The grid changes based on cell height and width.
Discussion
Although this extended abstract wasn't too informative, it did give me some thoughts about how we could use sketch recognition techniques to improve upon drawn passwords.
Monday, February 16, 2009
SKIT: A Computer-Assisted Sketch Instruction Tool
Greg Coombe and Brian Salomon
Department of Computer Science, University of North Carolina
This paper discusses a system, SKIT, that assists users in sketching line drawings by using some artist techniques. The system breaks a full outline sketch into subdrawings that the user can draw at various sizes. This allows the user to see the model they are drawing as a set of smaller, more geometric objects. The subdrawings are then merged back together in the end.
The small user study was more qualitative and showed users improved when using SKIT.
Discussion:
The paper presents a technique or two that might be helpful in starting a user-training program for sketching.
Department of Computer Science, University of North Carolina
This paper discusses a system, SKIT, that assists users in sketching line drawings by using some artist techniques. The system breaks a full outline sketch into subdrawings that the user can draw at various sizes. This allows the user to see the model they are drawing as a set of smaller, more geometric objects. The subdrawings are then merged back together in the end.
The small user study was more qualitative and showed users improved when using SKIT.
Discussion:
The paper presents a technique or two that might be helpful in starting a user-training program for sketching.
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