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Experimental Brain Research

, 193:287 | Cite as

Dual LATER-unit model predicts saccadic reaction time distributions in gap, step and appearance tasks

  • Giles W. Story
  • R. H. S. CarpenterEmail author
Research Article

Abstract

Saccadic latencies have long been known to depend on the relative timing of the appearance of the new target, and offset of the original fixation target. Previous studies have tended to conclude that two separate effects are at work, one equivalent to competitive inhibition from the fixation target, and the other due to its offset providing a warning that shortens latency. In this study, we propose a simpler explanation, based on a well-established model of reaction time, LATER (linear approach to threshold with ergodic rate), that in addition to predicting mean latencies also—more challengingly—predicts latency distributions. We show that observed distributions, using gap, step and appearance tasks under three conditions of prior probability, can be accurately predicted by using a pair of LATER units, one corresponding to fixation target offset and the other to peripheral target onset. Because fixation offset is probabilistically associated with target appearance, when the fixation unit is activated it increases the target’s decision signal (that represents probability) in a fixed proportion, speeding responses. In contrast, when the fixation target remains present, the fixation unit is not activated, and responses are slower. Both these effects generate characteristic changes in the shapes of the latency distributions that can be accurately predicted by the model.

Keywords

Saccade Reaction time Gap task LATER 

References

  1. Boot WR, Kramer AF, Peterson MS (2005) Oculomotor consequences of abrupt object onsets and offsets: onsets dominate oculomotor capture. Percep Psychophys 67:910–928Google Scholar
  2. Braun D, Breitmeyer BG (1990) Effects of reappearence of fixated and attended stimuli upon saccadic reaction time. Exp Brain Res 81:318–324PubMedCrossRefGoogle Scholar
  3. Camalier CR, Gotier A, Murthy A, Thompson KG, Logan GD, Palmieri TJ, Schall JD (2007) Dynamics of saccade target selection: race model analysis of doubl; step and search step saccade production in human and macaque. Vis Res 47:2187–2211PubMedCrossRefGoogle Scholar
  4. Carpenter RHS (1981) Oculomotor procrastination. In: Fisher DF, Monty RA, Senders JW (eds) Eye movements: cognition and visual perception. Lawrence Erlbaum, Hillsdale, pp 237–246Google Scholar
  5. Carpenter RHS, Williams MLL (1995) Neural computation of log likelihood in the control of saccadic eye movements. Nature 377:59–62PubMedCrossRefGoogle Scholar
  6. Dorris MC, Munoz DP (1995) A neural correlate for the gap effect on saccadic reaction times in monkeys. J Neurophysiol 73:2558–2562PubMedGoogle Scholar
  7. Dorris MC, Paré M, MUnoz DP (1997) Neuronal activity in monkey superior colliculus related to the initiation of saccadic eye movements. J Neurosci 17:8566–8579PubMedGoogle Scholar
  8. Fecteau JH, Munoz DP (2007) Warning signals influence motor processing. J Neurophysiol 97:1600–1609PubMedCrossRefGoogle Scholar
  9. Fischer B, Ramsperger E (1984) Human express saccades: extremely short reaction times of goal directed eye movements. Exp Brain Res 57:191–195PubMedCrossRefGoogle Scholar
  10. Gmeindl L, Rontal A, Reuter-Lorenz PA (2005) Strategic modulation of the fixation offset effect: dissociable effects of target probability on prosaccades and antisaccades. Exp Brain Res 164:199–204CrossRefGoogle Scholar
  11. Grice GR (1968) Stimulus intensity and response evocation. Psychol Rev 75:359–373PubMedCrossRefGoogle Scholar
  12. Hanes DP, Carpenter RHS (1999) Countermanding saccades in humans. Vis Res 39:2777–2791PubMedCrossRefGoogle Scholar
  13. Hikosaka O, Wurtz RH (1983) Visual and oculomotor functions of monkey substantia nigra pars reticulata. IV. Relation of substantia nigra to superior colliculus. J Neurophysiol 49:1285–1301PubMedGoogle Scholar
  14. Hikosaka O, Wurtz RH (1985a) Modification of saccadic eye movements by GABA-related substances. I. Effect of muscimol and bicuculline in monkey superior colliculus. J Neurophysiol 53:266–291PubMedGoogle Scholar
  15. Hikosaka O, Wurtz RH (1985b) Modification of saccadic eye movements by GABA-related substances. II. Effects of muscimol in monkey substantia nigra pars reticulata. J Neurophysiol 53:292–308PubMedGoogle Scholar
  16. Kalesnykas RP, Hallett PE (2002) Saccadic latency effects of progressively deleting stimulus offsest and onsets. Vis Res 42:637–652PubMedCrossRefGoogle Scholar
  17. Kolmogorov A (1941) Confidence limits for an unknown distribution function. Ann Math Stat 23:525–540Google Scholar
  18. Kopecz K (1995) Saccadic reaction times in gap/overlap paradigms: a model based of integration of intentional and visual information on neural, dynamic, fields. Vis Res 35:2911–2925PubMedCrossRefGoogle Scholar
  19. Lamabadusuriya HI, Martin RIR, Carpenter RHS (2004) The effect of distractors on saccadic latency. J Physiol 555P PC127Google Scholar
  20. Leach JCD, Carpenter RHS (2001) Saccadic choice with asynchronous targets: evidence for independent randomisation. Vis Res 41:3437–3445PubMedCrossRefGoogle Scholar
  21. Ludwig CJH, Gilchrist ID, McSorley E (2005) The remote distractor effect in saccade programming: channel interaction and lateral inhibition. Vis Res 45:1177–1190PubMedCrossRefGoogle Scholar
  22. Machado L, Rafal RD (2000) Strategic control over saccadic eye movements: studies of the fixation offset effect. Percept Psychophys 62:1236–1242PubMedGoogle Scholar
  23. Munoz DP, Wurtz RH (1993a) Fixation cells in monkey superior colliculus. 1. Characteristics of cell discharge. J Neurophysiol 70:559–575PubMedGoogle Scholar
  24. Munoz DP, Wurtz RH (1993b) Fixation cells in monkey superior colliculus. 2. Reversible activation and deactivation. J Neurophysiol 70:576–589PubMedGoogle Scholar
  25. Munoz DP, Istvan PS (1998) Lateral inhibitory interactions in the intermediate layers of the monkey superior colliculus. J Neurophysiol 79:1193–1209PubMedGoogle Scholar
  26. Oswal A, Ogden M, Carpenter RHS (2007) The time-course of stimulus expectation in a saccadic decision task. J Neurophysiol 97:2722–2730PubMedCrossRefGoogle Scholar
  27. Reddi B, Carpenter RHS (2000) The influence of urgency on decision time. Nat Neurosci 3:827–831PubMedCrossRefGoogle Scholar
  28. Reddi BAJ, Asrress KN, Carpenter RHS (2003) Accuracy, information and response time in a saccadic decision task. J Neurophysiol 90:3538–3546PubMedCrossRefGoogle Scholar
  29. Reulen JPH (1984a) Latency of visually evoked eye movements. I. Saccadic latency and the facilitation model. Biol Cybern 50:251–262PubMedCrossRefGoogle Scholar
  30. Reulen JPH (1984b) Latency of visually evoked saccadic eye movements. II. Temporal properties of the facilitation mechanism. Biol Cybern 50:263–271PubMedCrossRefGoogle Scholar
  31. Reuter-Lorenz PA, Hughes HC, Fendrich R (1991) The reduction of saccadic latencies by prior offset of the fixation point: an analysis of the gap effect. Percept Psychophys 49:167–175PubMedGoogle Scholar
  32. Reuter-Lorenz PA, Oonk HM, Barnes LL, Hughes HC (1995) Effects of warning signals and fixation point offsets on the latencies of pro-versus anti-saccades: implications for the interpretation of the gap effect. Exp Brain Res 103:287–293PubMedCrossRefGoogle Scholar
  33. Ross LE, Ross SM (1980) Saccade latency and warning signals: stimulus onset, offset, and change as warning events. Percept Psychophys 27:251–257PubMedGoogle Scholar
  34. Ross SM, Ross LE (1981) Saccade latency and warning signals: effects of auditory and visual onset and offset. Percept Psychophys 29:429–437PubMedGoogle Scholar
  35. Saslow MG (1967) Effects of components of displacement-step stimuli upon latency for saccadic eye movements. J Opt Soc Am 57:1024–1029PubMedCrossRefGoogle Scholar
  36. Taylor MJ, Carpenter RHS, Anderson AJ (2006) A noisy transform predicts saccadic and manual reaction times to changes in contrast. J Physiol 573:741–751PubMedCrossRefGoogle Scholar
  37. Trappenberg TP, Dorris MC, Munoz DP, Klein RM (2001) A model of saccadic initiation based on the competitive integration of exogneous and endogenous signals in the superior colliculus. J Cogn Neurosci 13:256–271PubMedCrossRefGoogle Scholar
  38. Walker R et al. (1997) Effect of remote distractors on saccadic programming: evidence for an extended fixation zone. J Neurophysiol 78:1096–1107Google Scholar
  39. Wenban-Smith MG, Findlay JM (1991) Express saccades: is there a separate population in humans? Exp Brain Res 87:218–222PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK

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