Grasping Movement Plans

By Rosenbaum, David A.; Halloran, Erin S. et al. | Psychonomic Bulletin & Review, October 2006 | Go to article overview

Grasping Movement Plans


Rosenbaum, David A., Halloran, Erin S., Cohen, Rajal G., Psychonomic Bulletin & Review


Despite the great amount of research that has been done regarding the time it takes to move the hand to targets of varying distances and widths, it is unclear whether target distance and width are both represented in movement plans prior to movement initiation. We addressed this question by studying performance in an object manipulation task. Our participants reached out and took hold of a familiar object (a bathroom plunger) to move it to wide or narrow targets of varying heights. Grasp heights on the plunger were additively affected by target height and target width, suggesting that both factors were taken into account by participants prior to moving the plunger from its initial position. Another factor we manipulated was the width of the base from which the plunger was lifted on its way to its next position. This factor also affected grasp heights, but no more so than target widths. The latter result contradicts the view that movement starts are planned in more detail than movement ends, as might be expected from the fact that movement starts come sooner. Together, our results suggest that forthcoming movements are planned in considerable detail. A surprising methodological implication of this study is that recording how people prepare to move can reveal as much-or in some cases more-about what they have planned than can recording their subsequent movements.

This study was designed to contribute to the understanding of the planning and control of physical actions and, in particular, actions involving object manipulation, an important functional activity and a rich venue for exploring the information actors have about their own bodies vis-à-vis the external environment (MacKenzie & Iberall, 1994). Our starting point was a classic observation by Fitts (1954) on the time it takes to move the hand from one point to another. Fitts found that this time increases as the distance between points increases, and that this time increases as the width of the target gets smaller. This dual influence of distance and target width on movement time has been demonstrated so many times and in such a wide range of conditions that the relation, or its more specific quantitative formulation (which need not be repeated here), has come to be called Fitts 's law (for a review, see Elliott, Helsen, & Chua, 2001).

How distance and target width are internally represented prior to movement initiation remains unclear from the many studies that have been done on Fitts's law. Are both factors represented, or is only one factor represented in advance, so that the unrepresented or minimally represented factor is only dealt with while movement is underway? If both factors are considered before movement initiation, are they considered independently or in some dependent fashion?

The available methods for addressing these questions have relied mainly on the kinematics of ongoing hand movements (i.e., the positions of the hand over time), but these methods have been less than wholly satisfactory in illuminating premovement planning. Such studies have generally shown that target width has an observable effect on observed movement speed later than does required distance. Thus, the starting phase of the movement is strongly affected by the distance to the target but is largely unaffected by the size of the target, whereas the ending phase of the movement is strongly affected by the size of the target but is less affected by the distance of the target from the launch point (for a review, see Elliott, Helsen, & Chua, 2001). Such observations suggest that homing in to smaller targets occurs late in movement, but they do not prove that target width is not considered prior to movement initiation. Planning with respect to target width could be carried out before movements start but not be manifested kinematically until movements are under way.

Given this uncertainty about the nature of movement planning for manual positioning movements, we sought another way to address the issue. …

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

Items saved from this article

This article has been saved
Highlights (0)
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.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
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, APA and Chicago citation styles.

(Einhorn, 1992, p. 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.

Cited article

Grasping Movement Plans
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

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, 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."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.

    Author Advanced search

    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.