Vernier thresholds were measured by means of a forced-choice paradigm for physically separated bars that were perceived either as separate or as amodally completed behind an occluder. The finding that thresholds were not reduced (improved) with amodal completion argues against an early neural code for amodal completion that is equivalent to physical completion of the vernier bars (ie neural propagation/interpolation) and limits the stage at which amodal representations could arise via bottom—up processes to neural sites located centrally with respect to those involved in position coding. An alternative explanation is also considered, that this result reflects the activity of top—down processes that mediate amodal completion by imposing grouping/organizational constraints upon earlier representations of position. In support of this proposition it was found that when tested by means of a non-forced-choice paradigm without feedback, observers demonstrated a reduced tendency to report the presence of a vernier offset when the bars were perceived as amodally completed (ie a shift in response bias occurred). This separability of vernier acuity and response bias suggests the existence of ‘top-but-not-very-far-down’ grouping processes whose influence does not extend to early representations of relative position.
Get full access to this article
View all access options for this article.
References
1.
AdelsonE H, 1984“Binocular disparity and the computation of two-dimensional motion”Journal of the Optical Society of America1284–299
2.
AdelsonE HMovshonJ A, 1982“Phenomenal coherence of moving visual patterns”Nature (London)300523–525
3.
BantonT, 1990Spatial Localization of Non-luminance Defined ContoursPhD thesis, University of Houston, Houston, Texas, USA
4.
BantonTLeviD M, 1989“Illusory contours act like low contrast real lines”Investigative Ophthalmology and Visual Science, Supplement 254
5.
BantonTLeviD M, 1991“Binocular summation in vernier acuity”Journal of the Optical Society of America A8673–680
6.
BarlowH BBlakemoreC BPettigrewJ D, 1967“The neural mechanism of binocular depth discrimination”Journal of Physiology (London)193327–342
7.
BradleyD R, 1987“Cognitive contours and perceptual organization”, in The Perception of Illusory Contours Eds PetrySMeyerG E (New York: Springer) pp 201–212
8.
BressanPGanisGVallortigaraG, 1993“The role of depth stratification in the solution of the aperture problem”Perception22215–228
9.
BurbeckC AHaddenS, 1993“Scaled position integration areas: Accounting for Weber's law for separation”Journal of the Optical Society of America A105–15
10.
DurginF HTripathyS PLeviD M, 1995“On the filling in of the visual blind spot: some rules of thumb”Perception (in press)
11.
FinneyD J, 1971Probit Analysis (Cambridge: Cambridge University Press)
12.
FioraniMJrRosaM G PGattassRRocha-MirandaC E, 1992“Dynamic surrounds of receptive fields in primate striate cortex: A physiological basis for perceptual completion?”Proceedings of the National Academy of Sciences of the United States of America898547–8551
13.
GattassRFioraniMJrRosaM G PPiñonM C G PDe SousaA P BSoaresJ G M, 1992“Visual responses outside the classical receptive field in primate striate cortex: A possible correlate of perceptual completion”, in The Visual System from Genesis to Maturity Ed. LentR (Boston, MA: Birkhäuser) pp 233–244
14.
GregoryR L, 1970The Intelligent Eye (New York: McGraw-Hill)
15.
GregoryR L, 1987“Illusory contours and occluding surfaces”, in The Perception of Illusory Contours Eds PetrySMeyerG E (New York: Springer) pp 81–89
16.
GrossbergSMingollaE, 1985“Neural dynamics of perceptual grouping: textures, boundaries, and emergent features”Perception & Psychophysics38141–171
17.
HeZ JNakayamaK, 1992“Surfaces versus features in visual search”Nature (London)359231–233
HeZ JNakayamaK, 1994b“Perceived surface shape not features determines correspondence strength in apparent motion”Vision Research342125–2136
20.
Von HelmholtzH, 1878/1971“The facts of perception”, in Selected Writings of Hermann von Helmholtz Ed. KahlR (Middleton, CT: Wesleyan University Press, 1971) pp 366–408 (original work published in 1879)
21.
HubelD HWieselT N, 1962“Receptive fields, binocular interaction and functional architecture in the cat's visual cortex”Journal of Physiology (London)160106–165
22.
HubelD HWieselT N, 1968“Receptive fields and functional architecture of monkey striate cortex”Journal of Physiology (London)195215–243
23.
KanizsaG, 1979Organization in Vision (New York: Praeger)
24.
KellmanP JShipleyT F, 1991“A theory of visual interpolation in object perception”Cognitive Psychology23141–221
25.
KleinS ALeviD M, 1986“Local multipoles for measuring contrast and phase sensitivity”Investigative Ophthalmology and Vision Science, Supplement 27225
26.
KleinS ALeviD M, 1987“Position sense of the peripheral retina”Journal of the Optical Society of America A41543–1553
27.
LeeB BWehrhahnCWestheimerGKremersJ, 1993“Macaque ganglion cell responses to stimuli that elicit hyperacuity in man: Detection of small displacements”Journal of Neuroscience131001–1009
28.
LeviD MKleinS A, 1990“The role of separation and eccentricity in encoding position”Vision Research30557–586
29.
LeviD MKleinS A, 1992“‘Weber's Law’ for position: the role of spatial frequency and contrast”Vision Research322235–2250
30.
LeviD MKleinS AYapY L, 1988“‘Weber's Law’ for position: unconfounding the role of separation and eccentricity”Vision Research28597–603
31.
LeviD MWaughS J, 1995“Position acuity with opposite polarity features: evidence for a nonlinear collator mechanism for position acuity?”Vision Research (in press)
32.
LiC-YLiW, 1994“Extensive integration field beyond the classical receptive field of cat's striate cortical neurons—classification and tuning properties”Vision Research342337–2355
33.
LotzeH, 1885Microcosmos (translated by HamiltonEConstance-JonesE E) (Edinburgh: T and T Clark)
34.
McKeeS PLeviD M, 1987“Dichoptic hyperacuity: the precision of nonius alignment”Journal of the Optical Society of America A41104–1108
35.
MarrD, 1982Vision (San Francisco, CA: W H Freeman)
36.
MeyerG EPetryS, 1987“Top-down and bottom-up: The illusory contour as a microcosm of issues in perception”, in The Perception of Illusory Contours Eds PetrySMeyerG E (New York: Springer) pp 3–20
37.
MoranJDesimoneR, 1985“Selective attention gates visual processing in the extrastriate cortex”Science229782–784
38.
MorganM JReganD, 1987“Opponent model for line interval discrimination: Interval and vernier performance compared”Vision Research27107–118
39.
MussapA JLeviD M, 1995a“Spatial properties of filters underlying vernier acuity revealed by masking: Evidence for collator mechanisms”Vision Research (in press)
40.
MussapA JLeviD M, 1995b“Binocular processes in vernier acuity”Journal of the Optical Society of America A121–9
41.
NakayamaKShimojoS, 1992“Experiencing and perceiving visual surfaces”Science2571357–1362
42.
NakayamaKShimojoSSilvermanG H, 1989“Stereoscopic depth: its relation to image segmentation, grouping, and the recognition of occluded objects”Perception1855–68
43.
ParadisoM ACarneyTFreemanR D, 1989“Cortical processing of hyperacuity tasks”Vision Research29247–254
44.
ParkerAHawkenM, 1985“Capabilities of monkey cortical cells in spatial-resolution tasks”Journal of the Optical Society of America A21101–1114
45.
RockI, 1987The Logic of Perception (Cambridge, MA: MIT Press)
46.
SekulerA BPalmerS E, 1992“Perception of partly occluded objects: A microgenetic analysis”Journal of Experimental Psychology: General12195–111
47.
SekulerA BSekulerR, 1993“Representational development of direction in motion perception: A fragile process”Perception22899–915
48.
ShapleyRVictorJ, 1986“Hyperacuity in cat retinal ganglion cells”Science231999–1002
49.
ShimojoSNakayamaK, 1990“Amodal representation of occluded surfaces: role of invisible stimuli in apparent motion correspondence”Perception19285–299
50.
ShimojoSSilvermanG HNakayamaK, 1989“Occlusion and the solution to the aperture problem”Vision Research29619–626
51.
SpitzerHDesimoneRMoranJ, 1988“Increased attention enhances both behavioral and neuronal performance”Science240338–340
52.
SwindaleN VCynaderM S, 1986“Vernier acuity of neurones in cat visual cortex”Nature (London)319591–593
53.
ToetA, 1987Visual Perception of Spatial OrderPhD thesis, Rijksuniversiteit te Utrecht, The Netherlands
WattR J, 1984“Towards a general theory of the visual acuities for shape and spatial arrangement”Vision Research241377–1386
59.
WattR JMorganM J, 1983“The recognition and representation of edge blur: evidence for spatial primitives in human vision”Vision Research231465–1477
60.
WattR JMorganM JWardR M, 1983“The use of different cues in vernier acuity”Vision Research23991–995
61.
WaughS JLeviD M, 1993“Visibility, timing and vernier acuity”Vision Research33505–526
62.
WaughS JLeviD MCarneyT, 1993“Orientation, masking, and vernier acuity for line targets”Vision Research331619–1638
63.
WeissteinN, 1970“Neural symbolic activity: A psychophysical measure”Science1681489–1491
64.
WeissteinWMontalvoF SOzogG, 1972“Differential adaptation to gratings blocked by cubes and gratings blocked by hexagons: A test of the neural symbolic activity hypothesis”Psychonomic Science2789–91
65.
WestheimerGMcKeeS P, 1977a“Integration regions for visual hyperacuity”Vision Research1789–93
66.
WestheimerGMcKeeS P, 1977b“Spatial configurations for visual hyperacuity”Vision Research17941–947
67.
WhitakerD, 1993“What part of a vernier stimulus determines performance?”Vision Research3327–32
68.
WhitakerDMacVeighD, 1991“Interaction of spatial frequency and separation in vernier acuity”Vision Research311205–1212
69.
WilsonH R, 1986“Responses of spatial mechanisms can explain hyperacuity”Vision Research26453–469
