The Detection of the Motion of Contrast Modulation: A Parametric Study

By Cropper, Simon J.; Kvansakul, Jessica G. S. et al. | Attention, Perception and Psychophysics, May 2009 | Go to article overview

The Detection of the Motion of Contrast Modulation: A Parametric Study


Cropper, Simon J., Kvansakul, Jessica G. S., Johnston, Alan, Attention, Perception and Psychophysics


Despite a long and productive history as a focus of research interest, the details of how humans detect motion in an image remain controversial. This debate has not been helped by the lack of a clear parametric description of motion discrimination for some of the more simple visual stimuli employed in the literature to date. With this in mind, in the present work, we examined a peculiarity observed in the perception of the motion of second-order (contrast-modulated) stimuli: Under certain stimulus conditions, there is a reversal in the perceived direction of motion of the pattern. The aim was to quantify this phenomenon, relate the reversal to forward (veridical) and ambiguous motion, and place the behavioral data in the context of the window of visibility model of spatiotemporal contrast sensitivity. The direction of motion of contrast-modulated patterns was measured as a function of temporal frequency and carrier contrast, under different critical stimulus conditions. The stimulus properties manipulated were spatial frequency, spatial-phase relationship of carrier and sidebands, color, duration, and, most critically, the retinal location of the stimulus. On a purely empirical basis, the data reconciled several conflicts in the recent literature. From a theoretical standpoint, the data were well explained by the window of visibility approach in the majority of conditions and were partially explained in the remaining conditions. The results raise some interesting questions about underlying motion detection mechanisms and the assumptions embodied in our approach to motion modeling and the visual system in general. Supplemental materials for this article may be downloaded from app.psychonomic-journals.org/content/supplemental.

The ability to accurately identify motion in an image is a critical property of the visual system, and one that has attracted a great deal of research interest over the past 30 years or so. However, despite the wealth of data collected and the extent of the confluence of that data, there is still uncertainty regarding how we detect the motion of the simplest luminance edge, let alone the more complex patterns employed in much of the recent research in motion psychophysics. It certainly appears that the motion detection system is a strongly hierarchical process and that the initial signal specific to the motion subsystem is related to the direction of motion of an edge (Lennie & Movshon, 2005; Marr, 1982). The edge is usually coded by a firstorder modulation of the image statistics (Cavanagh & Mather, 1989; Julesz, 1971), and the directional signal relating to any 1-D edge is accurate only to within 690?, a property known as the aperture problem (Marr & Ullman, 1981). From this relatively simple starting point, the signal is progressively built into a neural representation that is a remarkably complex and powerful contributor to the overall percept of the visual scene, revealing not only the motion in the input, but also the depth and, in some cases, the form (Warren, 2004). Furthermore, visual motion in an image is strongly linked to the change in apparent position of a perceptually consistent auditory signal, indicating its importance as a key signal facilitating the integration of the internal representation of the external environment as a whole (e.g., Kitagawa & Ichigara, 2002). The hierarchy of signal construction is seen in both the behavioral data (Wilson, Ferrera, & Yo, 1992) and the neurophysiological data (Duffy, 2004), evidence that, in turn, shapes the way in which we define and describe the stimuli that we use to further explore the issue.

An example of the influence of the apparent hierarchy is the description of a visual stimulus in terms of its firstorder and second-order spatial statistics and of the consideration of each spatial dimension (x and y) independently. Consistent with this, there has been an argument presented within the motion literature for independent pathways in the system that deal with the first-order and second-order components of the pattern separately (e. …

The rest of this article is only available to active members of Questia

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Note: primary sources have slightly different requirements for citation. Please see these guidelines for more information.

Cited article

The Detection of the Motion of Contrast Modulation: A Parametric Study
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this article
  • Highlights & Notes
  • Citations
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Search by... Author
    Show... All Results Primary Sources Peer-reviewed

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.