NASA Vision Group

<NASA Vision Group>
NASA Ames Research Center

Publications から文献閲覧が可能
Probability summation over time (1979)　Andrew B. Watson, Vision Research, 19, 515-52
など
References
http://vision.arc.nasa.gov/

What does the eye see best?

What does the eye see best?

Watson AB, Barlow HB, Robson JG.

Our eyes see so much in such varied conditions that one might consider the question posed in the title to be meaningless, but we show here that, within the range that we have been able to test, there is a particular spatiotemporal pattern of light that is detected better than any other. At least two plausible theories of visual detection predict that a stimulus will be seen best (will have greatest quantum efficiency) when it matches the weighting function of the most efficient detector. We have measured quantum efficiency for detecting a wide variety of spatiotemporal patterns using foveal vision in bright light. The best stimulus found so far is a small, briefly exposed circular patch of sinusoidal grating having a spatial frequency of approximately 7 c deg-1, drifting at approximately 4 Hz. We propose that this is the weighting function of the most efficient human contrast detector. We believe this answer to the question is unexpected and may have fundamental implications with regard to the mechanisms of visual perception.

References
Nature. 1983 Mar 31-Apr 6;302(5907):419-22.

Watson, A. B. & Ahumada, A. J., Jr. (2005)

Watson, A. B. & Ahumada, A. J., Jr. (2005). A standard model for foveal detection of spatial contrast. Journal of Vision, 5(9), 717-740.
Keywords
vision, spatial, pattern, detection, threshold, contrast, contrast sensitivity, model, ModelFest


References
http://journalofvision.org/5/9/6/

Watson, AB (1979)

Watson, A. B. (1979 ). Probability summation over time. Vision Research, 19, 515-522.

Abstract

Frequency-of-seeing and sensitivity-duration curves were collected for temporal signals of limited spectral extent. A comparison of the two sorts of data suggests that a stimulus is detected whenever the excursions of its linearly filtered, noise-perturbed temporal waveform exceed some fixed magnitude.

References
Elsevier.com - Vision Research
http://www.elsevier.com/wps/find/journaldescription.cws_home/263/description#description

アスキー形式のsave

行列Aをアスキー形式で保存
>> save 'A.mat' A -ascii
ファイル名を指定するときに 拡張子 .mat をつける必要があることに注意

データの読み込み
>> load 'A.mat' -ascii
ファイル名から拡張子をとった名前の変数にロードした結果が代入される

References
MATLAB入門編
http://feedback.mech.fukui-u.ac.jp/matlab/matlab0.htm

R による統計処理--データなどの入出力法

1. 作業ディレクトリを指定する
"Misc" メニューから，"Change Working Directory..." を選択し，作業ディレクトリを選ぶ。

2. テキストファイルからデータを読む
（データはテキストファイルとして用意するほうが汎用性が高い）
個々の変数の値が区切り文字（タブ，スペース，カンマなど）で区切られているテキストファイルからデータを読み込む
> x <- read.table("out.data", header=FALSE)
> x
1 行目からデータならば，header=FALSE

References
R による統計処理--データなどの入出力法
http://aoki2.si.gunma-u.ac.jp/R/io/index.html