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Invariance of primate object recognition

FIAS. Invariance of primate object recognition. By Thomas Weißwange. Outline. Introduction - Inferotemporal Cortex and Object Vision Ventral visual pathway Feature recognition cells in TE Afferents to TE Organisation of TE Receptive fields of IT/STS-neurons Crowding and Familiarity

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Invariance of primate object recognition

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  1. FIAS Invariance of primate object recognition By Thomas Weißwange

  2. Outline • Introduction - InferotemporalCortex and Object Vision • Ventral visual pathway • Feature recognition cells in TE • Afferents to TE • Organisation of TE • Receptive fields of IT/STS-neurons • Crowding and Familiarity • Conclusion

  3. Introduction – Ventral Visual Pathway Quelle: http://thebrain.mcgill.ca

  4. Introduction - Feature Recognition • Specific Stimuli Selection • Large receptive field including the fovea • Orientation-sensitivity • Size-dependent and –independent cells Orientation Size

  5. Introduction - Feature Recognition • Trained monkeys have more representations of the trained stimuli • They can also develop cells responsible for associative pairs

  6. Introduction – TE-Afferents • Few feature-cells also in TEO and V4 • Various levels of complexity • Cells from TEO projects only on to small focussed areas of TE

  7. Introduction - Organisation of TE • Columnar organisation (Respond to same Stimuli) • Maximal response at slightly different stimuli • Different features stimulate overlapping regions

  8. Introduction - Organisation of TE • A feature is represented by a whole column -> Large invariances through differences inside the column -> High discrimination through single-cell-response -> By overlappings the discrimination acuity can be very high

  9. Receptive Fields of IT/STS-Neurons • The problem of multiple objects • Influences of attention • Natural scenes

  10. Receptive Fields of IT/STS-Neurons • Firing rate at fixation does not change much („Background Invariance“, „Association Invariance“) • Receptive field size differs with background

  11. Receptive Fields of IT/STS-Neurons • Attention only has an effect on the receptive field • A second stimulus decreases field size

  12. Crowding and Familiarity • Crowding: • Impairement of recognizability by neighbouring objects within a „critical spacing“ • Familiarity: • Context dependent improvement/impairment of recognizability

  13. Crowding and Familiarity thin or fat

  14. Crowding and Familiarity • Critical spacing increases with eccentricity, independent of size • Critical spacing is roughly half of the eccentricity

  15. Crowding and Familiarity • Context improves recognition at low, hinders at high eccentricities • Crowding has a bigger impact on recognition than familiarity

  16. Conclusion • Invariance of Object Recognition originate from groups of neurons with similar specific stimuli but differences in attributes of those • Receptive fields depend on backgrounds • Object Recognition depends on feature-context

  17. Quellen • K. Tanaka, Inferotemporal Cortex and Object Vision, Annu. Rev. Neurosci., 1996 • E.T. Rolls et al., The Receptive Fields of Inferior Tempral Cortex Neurons in Natural Scenes, J. Neurosci., 2003 • M. Martelli et al., Are faces processed like words? A diagnostic test for recognition by parts, Journal of Vision, 2005. Thank you for your attention

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