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. 2002 Aug 7;269(1500):1571–1579. doi: 10.1098/rspb.2002.2062

The timing of sequences of saccades in visual search.

E M Van Loon 1, I Th C Hooge 1, A V Van den Berg 1
PMCID: PMC1691069  PMID: 12184827

Abstract

According to the LATER model (linear approach to thresholds with ergodic rate), the latency of a single saccade in response to target appearance can be understood as a decision process, which is subject to (i) variations in the rate of (visual) information processing; and (ii) the threshold for the decision. We tested whether the LATER model can also be applied to the sequences of saccades in a multiple fixation search, during which latencies of second and subsequent saccades are typically shorter than that of the initial saccade. We found that the distributions of the reciprocal latencies for later saccades, unlike those of the first saccade, are highly asymmetrical, much like a gamma distribution. This suggests that the normal distribution of the rate r, which the LATER model assumes, is not appropriate to describe the rate distributions of subsequent saccades in a scanning sequence. By contrast, the gamma distribution is also appropriate to describe the distribution of reciprocal latencies for the first saccade. The change of the gamma distribution parameters as a function of the ordinal number of the saccade suggests a lowering of the threshold for second and later saccades, as well as a reduction in the number of target elements analysed.

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Selected References

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  1. Carpenter R. H., Williams M. L. Neural computation of log likelihood in control of saccadic eye movements. Nature. 1995 Sep 7;377(6544):59–62. doi: 10.1038/377059a0. [DOI] [PubMed] [Google Scholar]
  2. Dorris M. C., Munoz D. P. Saccadic probability influences motor preparation signals and time to saccadic initiation. J Neurosci. 1998 Sep 1;18(17):7015–7026. doi: 10.1523/JNEUROSCI.18-17-07015.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Findlay J. M., Walker R. A model of saccade generation based on parallel processing and competitive inhibition. Behav Brain Sci. 1999 Aug;22(4):661–721. doi: 10.1017/s0140525x99002150. [DOI] [PubMed] [Google Scholar]
  4. Fischer B., Weber H., Biscaldi M., Aiple F., Otto P., Stuhr V. Separate populations of visually guided saccades in humans: reaction times and amplitudes. Exp Brain Res. 1993;92(3):528–541. doi: 10.1007/BF00229043. [DOI] [PubMed] [Google Scholar]
  5. Glimcher P. W. Making choices: the neurophysiology of visual-saccadic decision making. Trends Neurosci. 2001 Nov;24(11):654–659. doi: 10.1016/s0166-2236(00)01932-9. [DOI] [PubMed] [Google Scholar]
  6. Hanes D. P., Carpenter R. H. Countermanding saccades in humans. Vision Res. 1999 Aug;39(16):2777–2791. doi: 10.1016/s0042-6989(99)00011-5. [DOI] [PubMed] [Google Scholar]
  7. Hanes D. P., Patterson W. F., 2nd, Schall J. D. Role of frontal eye fields in countermanding saccades: visual, movement, and fixation activity. J Neurophysiol. 1998 Feb;79(2):817–834. doi: 10.1152/jn.1998.79.2.817. [DOI] [PubMed] [Google Scholar]
  8. Hanes D. P., Schall J. D. Neural control of voluntary movement initiation. Science. 1996 Oct 18;274(5286):427–430. doi: 10.1126/science.274.5286.427. [DOI] [PubMed] [Google Scholar]
  9. Hooge I. T., Beintema J. A., van den Berg A. V. Visual search of heading direction. Exp Brain Res. 1999 Dec;129(4):615–628. doi: 10.1007/s002210050931. [DOI] [PubMed] [Google Scholar]
  10. Hooge I. T., Erkelens C. J. Adjustment of fixation duration in visual search. Vision Res. 1998 May;38(9):1295–1302. doi: 10.1016/s0042-6989(97)00287-3. [DOI] [PubMed] [Google Scholar]
  11. Hooge I. T., Erkelens C. J. Control of fixation duration in a simple search task. Percept Psychophys. 1996 Oct;58(7):969–976. doi: 10.3758/bf03206825. [DOI] [PubMed] [Google Scholar]
  12. Itti L., Koch C. A saliency-based search mechanism for overt and covert shifts of visual attention. Vision Res. 2000;40(10-12):1489–1506. doi: 10.1016/s0042-6989(99)00163-7. [DOI] [PubMed] [Google Scholar]
  13. Kim J. N., Shadlen M. N. Neural correlates of a decision in the dorsolateral prefrontal cortex of the macaque. Nat Neurosci. 1999 Feb;2(2):176–185. doi: 10.1038/5739. [DOI] [PubMed] [Google Scholar]
  14. Leach J. C., Carpenter R. H. Saccadic choice with asynchronous targets: evidence for independent randomisation. Vision Res. 2001;41(25-26):3437–3445. doi: 10.1016/s0042-6989(01)00059-1. [DOI] [PubMed] [Google Scholar]
  15. McPeek R. M., Skavenski A. A., Nakayama K. Concurrent processing of saccades in visual search. Vision Res. 2000;40(18):2499–2516. doi: 10.1016/s0042-6989(00)00102-4. [DOI] [PubMed] [Google Scholar]
  16. McPeek Robert M., Keller Edward L. Superior colliculus activity related to concurrent processing of saccade goals in a visual search task. J Neurophysiol. 2002 Apr;87(4):1805–1815. doi: 10.1152/jn.00501.2001. [DOI] [PubMed] [Google Scholar]
  17. Munoz D. P., Wurtz R. H. Fixation cells in monkey superior colliculus. I. Characteristics of cell discharge. J Neurophysiol. 1993 Aug;70(2):559–575. doi: 10.1152/jn.1993.70.2.559. [DOI] [PubMed] [Google Scholar]
  18. Munoz D. P., Wurtz R. H. Fixation cells in monkey superior colliculus. II. Reversible activation and deactivation. J Neurophysiol. 1993 Aug;70(2):576–589. doi: 10.1152/jn.1993.70.2.576. [DOI] [PubMed] [Google Scholar]
  19. Munoz D. P., Wurtz R. H. Saccade-related activity in monkey superior colliculus. I. Characteristics of burst and buildup cells. J Neurophysiol. 1995 Jun;73(6):2313–2333. doi: 10.1152/jn.1995.73.6.2313. [DOI] [PubMed] [Google Scholar]
  20. Munoz D. P., Wurtz R. H. Saccade-related activity in monkey superior colliculus. II. Spread of activity during saccades. J Neurophysiol. 1995 Jun;73(6):2334–2348. doi: 10.1152/jn.1995.73.6.2334. [DOI] [PubMed] [Google Scholar]
  21. Rayner K. Eye movements in reading and information processing: 20 years of research. Psychol Bull. 1998 Nov;124(3):372–422. doi: 10.1037/0033-2909.124.3.372. [DOI] [PubMed] [Google Scholar]
  22. Reddi B. A., Carpenter R. H. The influence of urgency on decision time. Nat Neurosci. 2000 Aug;3(8):827–830. doi: 10.1038/77739. [DOI] [PubMed] [Google Scholar]
  23. Robinson D. A. Eye movements evoked by collicular stimulation in the alert monkey. Vision Res. 1972 Nov;12(11):1795–1808. doi: 10.1016/0042-6989(72)90070-3. [DOI] [PubMed] [Google Scholar]
  24. Shadlen M. N., Britten K. H., Newsome W. T., Movshon J. A. A computational analysis of the relationship between neuronal and behavioral responses to visual motion. J Neurosci. 1996 Feb 15;16(4):1486–1510. doi: 10.1523/JNEUROSCI.16-04-01486.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Sommer M. A. The spatial relationship between scanning saccades and express saccades. Vision Res. 1997 Oct;37(19):2745–2756. doi: 10.1016/s0042-6989(97)00078-3. [DOI] [PubMed] [Google Scholar]
  26. Sommer M. A., Wurtz R. H. Composition and topographic organization of signals sent from the frontal eye field to the superior colliculus. J Neurophysiol. 2000 Apr;83(4):1979–2001. doi: 10.1152/jn.2000.83.4.1979. [DOI] [PubMed] [Google Scholar]
  27. Sparks D., Rohrer W. H., Zhang Y. The role of the superior colliculus in saccade initiation: a study of express saccades and the gap effect. Vision Res. 2000;40(20):2763–2777. doi: 10.1016/s0042-6989(00)00133-4. [DOI] [PubMed] [Google Scholar]
  28. Zelinsky G. J., Sheinberg D. L. Eye movements during parallel-serial visual search. J Exp Psychol Hum Percept Perform. 1997 Feb;23(1):244–262. doi: 10.1037//0096-1523.23.1.244. [DOI] [PubMed] [Google Scholar]
  29. Zingale C. M., Kowler E. Planning sequences of saccades. Vision Res. 1987;27(8):1327–1341. doi: 10.1016/0042-6989(87)90210-0. [DOI] [PubMed] [Google Scholar]

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