Brain Modularity

Brain Modularity
Using the your school Online Library; find two peer-reviewed journal articles on brain modularity, with a focus on visual sensation and perception. In your synopsis, you will include:

  • A summary of each of the journal articles
  • The main points discussed in each of the journal articles and how they relate to the week’s course and text readings
  • Your thoughts and perspectives regarding the concepts covered in each of the journal articles

Submission Details:

  • Name your document: SU_PSY3400_W2_Project_LastName_FirstInitial
  • Submit your report in a Microsoft Word document to the Submissions Area by the due date assigned.
  • Using APA format, cite sources appropriately throughout your assignment, and reference on a separate page.
    Brain Topography, Volume 18, Number 2, Winter 2005 (©2005) 67 DOI: 10.1007/s10548-005-0276-8
    Borowsky et al.68
    Modularity and Intersection 69
    Borowsky et al.70
    Modularity and Intersection 71
    Borowsky et al.72
    Modularity and Intersection 73
    Borowsky et al.74
    Modularity and Intersection 75
    Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

    218
    Perceiving visually presented objects: recognition, awareness, and modularity Anne M Treisman* and Nancy G Kanwisherf
    Object perception may involve seeing, recognition,
    preparation of actions, and emotional responses-functions
    that human brain imaging and neuropsychology suggest are
    localized separately. Perhaps because of this specialization,
    object perception is remarkably rapid and efficient.
    Representations of componential structure and interpolation
    from view-dependent images both play a part in object
    recognition. Unattended objects may be implicitly registered,
    but recent experiments suggest that attention is required to
    bind features, to represent three-dimensional structure, and to
    mediate awareness.
    Addresses *Department of Psychology, Princeton University, Princeton, New Jersey 08544-1010, USA; e-mail: treisman@phoenix.princeton.edu tDepartment of Brain and Cognitive Sciences, El O-243, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA; e-mail: ngk@psyche.mit.edu
    Current Opinion in Neurobiology 1998, 8:218-226
    http://biomednet.com/elecref/0959438800800218
    0 Current Biology Ltd ISSN 0959-4388
    Abbreviations
    ERP event-related potential fMRl functional magnetic resonance imaging IT inferotemporal cortex
    Introduction It is usually assumed that perception is mediated by specific patterns of neural activity that encode a selective
    description of what is seen, distinguishing it from other
    similar sights. When we perceive an object, we may form
    multiple representations, each specialized for a different
    purpose and therefore selecting different properties to
    encode at different levels of detail. There is empirical
    evidence supporting the existence of six different types
    of object representation. First, representation as an ‘object
    token’-a conscious viewpoint-dependent representation
    of the object as currently seen. Second, as a ‘structural de-
    scription’- a non-visually-conscious object-centered rep-
    resentation from which the object’s appearance from other
    angles and distances can be predicted. Third, as an
    ‘object type’-a recognition of the object’s identity (e.g. a
    banana) or membership in one or more stored categories.
    Fourth, a representation based on further knowledge
    associated with the category (such as the fact that the
    banana can be peeled and what it will taste like). Fifth, a
    representation that includes a specification of its emotional
    and motivational significance to the observer. Sixth, an
    ‘action-centered description’, specifying its “affordances”
    [l], that is, the properties we need in order to program
    appropriate motor responses to it, such as its location,
    size and shape relative to our hands. These different
    representations are probably formed in an interactive
    fashion, with prior knowledge facilitating the extraction of
    likely features and structure, and vice versa.
    Evidence suggests that the first four types of encoding
    depend primarily on the ventral (occipitotemporal) path-
    way, the fifth on connections to the amygdala, and the
    sixth on the dorsal (occipitoparietal) pathway; however,
    object tokens have also been equated with action-centered
    descriptions [PI. Dorsal representations appear to be
    distinct from those that mediate conscious perception;
    for example, grasping is unaffected by the Titchener
    size illusion [3]. Emotional responses can also be evoked
    without conscious recognition (e.g. see [4**]). Object
    recognition models differ over whether the type or identity
    of objects is accessed from the view-dependent token or
    from a structural description; in some cases, it may also be
    accessed directly from simpler features.
    The goal of perception is to account for systematic
    patterning of the retinal image, attributing features to their
    real world sources in objects and in the current viewing
    conditions. In order to achieve these representations,
    multiple sources of information are used, such as color,
    luminance, texture, relative size, dynamic cues from mo-
    tion and transformations, and stereo depth; however, the
    most important is typically shape. Many challenges arise in
    solving the inverse problem of retrieving the likely source
    of the retinal image: information about object boundaries
    is often incomplete and noisy; and three-dimensional
    objects are seen from multiple views, producing different
    two-dimensional projections on the retina, and objects in
    normal scenes are often partially occluded. The visual
    system has developed many heuristics for solving these
    problems. Continuity is assumed rather than random varia-
    tion. Regularities in the image are attributed to regularities
    in the real world rather than to accidental coincidences.
    Different types of objects and different levels of specificity
    require diverse discriminations, making it likely that
    specialized modules have evolved, or developed through
    learning, to cope with the particular demands of tasks
    such as face recognition, reading, finding our way through
    places, manipulating tools, and identifying animals, plants,
    minerals and artifacts.
    Research on object perception over the past year has made
    progress on a number of issues. Here, we will discuss
    recent advances in our understanding of the speed of
    object recognition, object types and tokens, and attention
    and awareness in object recognition. In addition, we will
    Perceiving visually presented objects Treisman and Kanwisher 219
    review evidence for cortical specializations for particular
    components of visual recognition.
    The speed of object recognition Evolutionary pressures have given high priority to speed
    of visual recognition, and there is both psychological and
    neuroscientific evidence that objects are discriminated
    within one or two hundred milliseconds. Behavioral
    studies have demonstrated that we can recognize up to
    eight or more objects per second, provided they are
    presented sequentially at fixation, making eye movements
    unnecessary [S]. Although rate measurements cannot tell
    us the absolute amount of time necessary for an individual
    object to be recognized, physiological recordings reveal
    the latency at which the two stimulus classes begin to
    be distinguished. Thorpe et al. [6”] have demonstrated significant differences in event-related brain potential
    (ERP) waveforms for viewing scenes containing animals
    versus scenes not containing animals at 150 ms after stim-
    ulus onset. Several other groups [7,8*,9-111 have found
    face-specific ERPs and magnetoencephalography (MEG)
    waveforms with latencies of 155-190 ms. DiGirolamo and
    Kanwisher (G DiGirolamo, NG Kanwisher, abstract in
    Psychonom Sot 1995, 305) found ERP differences for line drawings of familiar versus unfamiliar three-dimensional
    objects at 170 ms (see also [S]).
    Parallel results were found in the stimulus selectivity
    of early responses of cells in inferotemporal (IT) cortex
    in macaques, initiated at latencies of 80-looms. On
    the basis that IT cells are selective for particular faces
    even in the first 50ms of their response, Wallis and
    Rolls [12] conclude that “visual recognition can occur
    with largely feed-forward processing”. The duration of
    responses by these face-selective cells was reduced from
    250ms to 25 ms by a backward mask appearing 20ms
    after the onset of the face, a stimulus onset asynchrony
    at which human observers can still just recognize the
    face. The data suggest that “a cortical area can perform
    the computation necessary for the recognition of a visual
    stimulus in ZO-30ms”. Thus, a consensus is developing
    that the critical processes involved in object recognition
    are remarkably fast, occurring within lOO-200ms of
    stimulus presentation. However, it may take another
    1OOms for subsequent processes to bring this information
    into awareness.
    Object tokens How then does the visual system solve the problems of
    object perception with such impressive speed and accu-
    racy? A first stage must be a preliminary segregation of the
    sensory data that form separate candidate objects. Even
    at this early level, familiarity can override bottom-up cues
    such as common region and connectedness, supporting
    an interactive cascade process in which “partial results of
    the segmentation process are sent to higher level object
    representations”, which, in turn, guide the segmentation
    process [ 13.1.
    Kahneman, Treisman, and Gibbs [14] have proposed
    that conscious seeing is mediated by episodic ‘object
    files’ within which the object tokens defined earlier
    are constructed. Information about particular instances
    currently being viewed is selected from the sensory
    array, accumulates over time, and is ‘bound’ together in
    structured relations. Evidence for this claim came partly
    from the observation of ‘object-specific’ priming- that
    is, priming that occurs only, or more strongly, when the
    prime and probe are seen as a single object. This occurs
    even when they appear in different locations, if the
    object is seen in real or apparent motion between the
    two. Object-specific priming occurs between pictures and
    names when these are perceptually linked through the
    frames in which they appear (RD Gordon, DE Irwin,
    personal communication), suggesting that object files
    accumulate information not only about sensory features
    but also about more abstract identities. However, priming
    between synonyms or semantic associates is not object
    specific [15], that is, it occurs equally whether they
    are presented in the same perceptual object or in
    different objects. It appears that object files integrate
    object representations with their names, but maintain
    a distinct identity from other semantically associated
    objects. Priming at this level would be between object
    types rather than tokens. Irwin [ 161 has reviewed evidence on transsaccadic integration, suggesting that it is limited to
    about four object files.
    A similar distinction between tokens and types has
    emerged from the study of repetition blindness, a failure
    to see a second token of the same type, which was
    attributed to refractoriness in attaching a new token to
    a recently instantiated type [17]. Recent research has
    further explored this idea. One role of object tokens is
    to maintain spatiotemporal continuity of objects across
    motion and change. Chun and Cavanagh [18”] confirmed
    that repetition blindness is greater when repeated items
    are seen to occur within the same apparent motion
    sequence and hence are integrated as the same perceived
    object. They suggest that perception is biased to minimize
    the number of different tokens formed to account for the
    sensory data. Objects that appear successively are linked
    whenever the spatial and temporal separations make
    this physically plausible. This generally gives veridical
    perception because in the real world, objects seldom
    appear from nowhere or suddenly vanish. Arnell and
    Jolicoeur [ 191 have demonstrated repetition blindness for novel objects for which no pre-existing representations
    existed. According to Kanwisher’s account [ 171, this implies that a single presentation is sufficient to establish
    an object type to which new tokens will be matched.
    The ‘attentional blink’ [ZO] describes a failure to de-
    tect the second of two different targets when it is
    presented soon after the first. Chun (21’1 sees both
    repetition blindness and the attentional blink as failures
    of tokenization, although for different reasons, because
    220 Cognitive neuroscience
    they can be dissociated experimentally. Attentional blinks
    (reduced by target-distractor discriminability) reflect a
    Di I,ollo, JT Enns, personal communication). The account proposed
    is that awareness depends on a match between re-entrant
    information and the current sensory input at early
    visual levels. A mismatch erases the initial tentative
    representation. “It is as though the visual system treats the
    trailing configuration as a transformation or replacement
    of the earlier one.” Conversely, repetition blindness for
    locations (R Epstein, NG Kanwisher, abstract in Psychononz
    Sot 1996, 593) may result when the representation of an
    earlier-presented letter prevents the stable encoding of
    a subsequently presented letter appearing at the same
    location.
    Attention and awareness in object perception Attention seems, then, to be necessary for object tokens
    to mediate awareness. However, there is evidence (see
    [Z-l’]) that objects can be identified without attention
    and awareness. If this is so, do the representations differ
    from those formed with attention? Activation (shown
    by brain-imaging) in specialized regions of cortex for
    processing faces [26] and visual motion [27] is reduced
    when subjects direct attention away from the faces or
    moving objects (respectively), even when eye movements
    are controlled to guarantee identical retinal stimulation
    (see also [28]), consistent with the effects of attention
    on single units in macaque visual cortex. Unattended
    objects are seldom reportable. However, priming studies
    suggest that their shapes can be implicitly registered
    [?.9,30**], although there are clear limits to the number of
    unattended objects that will prime [31]. Representations
    formed without attention may differ from those that
    receive attention: they appear to be viewpoint-dependent
    [32’], two-dimensional, with no interpretation of occlusion
    or amodal completion [30”]. On the other hand, in
    clinical neglect, the ‘invisible’ representations formed in
    a patient’s neglected field include illusory contours and
    filled-in surfaces [33-l, suggesting that neglect arises at
    stages of processing beyond those that are suppressed in
    normal selective attention. With more extreme inattention,
    little explicit information is available beyond simple
    features such as location, color, size, and gross numerosity;
    even these simple features may not be available, produc-
    ing ‘inattentional blindness’ [34’]. Again, however, some
    implicit information is registered: unseen words may prime
    word fragment completion, and there is clear selectivity
    for emotionally important objects such as the person’s own
    name and happy (but not sad) faces.
    Binding of features to objects is often inaccurate unless
    attention is focused on the relevant locations [35].

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