Convergence

Convergence, a second bodily source of information about depth, a binocular cue. When you look at a distant object, the lines of vision from your eyes are parallel. However, when you look at something 50 feet or less in distance, your eyes must converge (turn in) to focus the object. Whenever you estimate a distance under 50 feet (as when you approach a stop sign, play catch, or zap flies with your personal laser), you are using convergence. There is a relationship here between muscle sensations and distance. Convergence is controlled by a group of muscles attached to the eyeball. These muscles feed information on eye position to the brain to help it judge distance. You can feel convergence by exaggerating it: Focus on your fingertip and bring it toward your eyes until they almost cross. At that point, you can feel the sensations from the muscles that control eye movement. [Coon, Dennis. Introduction to Psychology, Exploration and Application. St. Paul: West Publishing Company, 1989 - The chapter on Perceiving]

R  E  F  E  R  E  N  C  E  S 

Converge vb [LL convergere, fr. L com- + vergere to bend, incline -more at Wrench] vi [1691] 1: to tend or move toward one point or one another; come together: Meet 2: to come together and unite in a common interest or focus -vt: to cause to converge

Convergent adj [1751] 1: tending to move toward one point or to approach each other: converging [__ lines] 2: exhibiting convergence in form, function, or development [__ evolution] 3a: characterized by having the nth term or the sum of the first n terms approach a finite limit [a __ sequence] [a __ series]

Converging lens n [18460]: a lens that causes parallel rays [as of light] to come to a focus

[Merriam-Webster's Collegiate Dictionary, 10th Edition. Springfield, MA, USA: Merriam-Webster, Inc. 1995.]

Depth. 1. a dimension taken through an object or body of material, usually downward or horizontally inward. 2. the quality of being deep; deepness. 3. complexity or obscurity, as of a subject. 4. gravity; seriousness. 5. emotional profundity. 6. intensity, as of silence, color, etc. 7. lowness of tonal pitch: the depth of a voice. 8. Often depths. a deep part or place. 9. Sometimes, depths. the farthest, innermost, or extreme part or state: the depth of space; the depth of the forest; the depths of despair. 10. Usually, depths. a low intellectual or moral condition: How could he sink to such depth? 11. the part of greatest intensity, as of night or winter. 12. in depth, extensively or thoroughly. -adj. 13. done or conducted in depth: a depth study; a depth interview. [ME depthe. See DEEP, -TH1] -Ant. 2. shallowness

Deep [ME dep. OE déop; akin to Goth diup(s), OIcel djup(r), OHG tiof] -Syn. 10. recondite, mysterious, obscure. 17. sagacious, wise, profound, shrewd. -Ant. 1,7,12,17 shallow.

[Urdang, Laurence, ed. Random House Dictionary of The English Language. New York: Random House,1968.]

1 Deep adj [ME dep. fr. OE déop; akin to OHG tiof deep, OE dyppan to dip -more at Dip] [Bef 12c] 1: extending far from some surface or area; as a: extending far downward [a __ well] b[1]: extending well inward from an outer surface [a __ gash] [a deep-chested animal] [2]: not located superficially within the body [__ pressure receptors in muscles] c: extending well back from a surface accepted as front [a __ closet] d: extending far laterally from the center [__ borders of place] e: occurring or located near the outer limits of the playing area [hit to __ right field] f: thrown deep [a __ pass] 2: having a specified extension in an implied direction usu . downward or backward [a shelf 20 inches __] [cars parked three-deep] 3a: difficult to penetrate or comprehend: Recondite [__ mathematical problems] b: Mysterioius, Obscure [a __ dark secret] c: grave in nature or effect [in __est disgrace] d: of penetrating intellect: Wise [a __ thinker] e: Involved, Engrossed [__ in debt] f: chracterized by profundity of feeling or quality [a __ sleep]; also: deep-seated [__ religious beliefs] 4a of color: high in saturation and low in lightness b: having a low musical pitch or pitch range [a __ voice] 5a: situated well within the boundaries [a house __ in the woods] b: remote in time or space c: being below the level of the conscious [__ neuroses] d: covered, enclosed, or filled to a specified degree -usu. used in combination [ankle-deep in mud] 6: Large [__ discounts] 7: having many good players [a __ bull pen] -syn see Broad -in deep water: in difficulty or distress

2 Deep adv [bef 12c] 1a: a vast or immeasurable extent: Abyss b [1]: the extent of surrounding space or time [2]: Ocean 2: any of the deep portions of a body of water; specif: a generally long and narrow area in the ocean where the depth exceeds 3000 fathoms [5500 meters] 3: the middle or most intense part [the __ of winter] 4: any of the fathom points on a sounding line other than the marks

Depth n [ME, prob. fr. dep deep] [14c] 1a: [1]: a deep place in a body of water [2]: a part that is far from the outside or surface [the __s of the woods] [3]: Abyss2 b [1]: a profound or intense state [as of thought or feeling] [the __s of misery]; also: a reprehensibly low condition [hadn't realized that standards had fallen to such __s] [2]: the middle of a time [as winter] [3]: the worst part 2a: the perpendicular measurement downward from a surface b: the direct linear measurement from front to back 3: the quality of being deep 4: the degree of intensity [__ of a color]: also: the quality of being profound [as in insight] or full [as of knowledge] 5: the quality or state of being complete or thorough [a study will be made in __]

Depth of field [1911]: the ragne of distances of the object in front of an image-forming device [as a camera lens] measured along the axis of the device throughout which the image has acceptable sharpness

Depth perception n [ca. 1911]: the ability to judge the distance of objects and the spatial relationship of objects at different distances