MAKING MEANING OF COMPLEX PATTERNS

Neil H. SchwartzPsych 401: Senior Seminar

Neuroanatomic Level: Basic Structures Lateral Occipital Cortex (LOC)

Plays an important role in human object recognition. V1

Each V1 transmits information to two primary pathways-- the dorsal stream and the ventral stream: The dorsal stream  is associated with motion, representation of object locations, and control of the eyes

and arms, especially when visual information is used to guide saccades or reaching. [1]

The ventral stream is associated with form recognition and object representation. It is also associated with storage of long-term memory.

V2 Has many properties in common with V1. Tuned to simple properties such as orientation, spatial frequency, and color, moderately complex

patterns, and whether the stimulus is part of the figure or the ground.+ V4

V4 is the first area in the ventral stream to show strong attentional modulation. Tuned for orientation, spatial frequency, and color. Unlike V1, V4 is tuned for object features of

intermediate complexity, like simple geometric shapes. Visual area V4 is not tuned for complex objects such as faces, as are areas in the inferotemporal

cortex . Inferotemporal cortex (IT)

 Crucial for visual object recognition and is considered to be the final stage in the ventral cortical visual system.

 Selective for the shape or color of a stimulus and respond more to complex than simple shapes. A small percentage of IT units are selective for facial images. Can be modulated by attention. Can show both short or long term memory for visual stimuli and their selectivity can be modified by

experience.

Anatomical Level: Fusiform Gyrus

The magic of the FUSIFORM GYRUS1. Responsible for interpreting complex patterns, like faces places, color, words, etc.

2. It is also trainable.

For example, bird watchers get better at recognizing species with practice.That is, the FG turns on after practice; but without the practice, it does not.

3. It is smaller in people with Autism.4. It moderates amygdala activation– at

least with potentially threatening faces causing avoidance behavior following a fear response but only when it is activated.

Theoretical Level: Explanatory Models: Geon Theory Geon Theory: Geon theory assumes that objects are

represented as an arrangement of simple, viewpoint-invariant, volumetric primitives, termed geons, such as bricks, cylinders, wedges, cones, etc.

A “geons” is a “geometric ion.” The term “ion” translates to “component or element,”

The idea is that we recognize faces (and other objects in our environment) by breaking them into geometric elements.

Biederman identified about 30 basic shapes and said that whenever we see something, our mind quickly “understands” it as an ordered collection of those basic shapes.

Theoretical Level: Explanatory Models: Visual Gist Perception Rapid characterization of a scene. People can identify a scene within 100

milliseconds. This discounts Geon Theory.

Recognizing patterns of patterns based on the typical spatial feature components common to scenes. E.g. cityscapes, playground at a park, beaches, etc.

Theoretical Level: Explanatory Models: Visual Gist Perception Scene gist has a powerful influence on how

we see an object embedded in a scene. The IT cortex has many sub-regions

specialized for object identification– pattern processing clusters.

The more clusters we need, the more neurons recruited; the more they become tuned for specific patterns. (chefs, dance critics, fly fisherman, etc.)

Theoretical Level: Explanatory Models: Visual Gist Perception

How is it researched?

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Cognitive Explanation: The Role of Working Memory: Visual and Verbal

“An entity in visual working memory can be thought of as a temporary grouping or nexus, where links are formed between active visual patterns derived from the visual image on the retina scene information and information relating to non-visual stored meanings– either verbal, motor, tactile, etc.”

Cognitive Explanation: The Role of Working Memory: Verbal WM Temporary transitory store Can hold speech information for 2

seconds. Called an echoic loop.

Cognitive Explanation: The Role of Working Memory: Attentional Processes Create temporary bindings of visual and verbal

material in working memory. Bindings come about as a result of control processes.

“Cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task.”

Cognitive Explanation: The Role of Long-term Memory

LTM is not a distinct unit; it is distributed all over the brain.

Every neuron both processes and stores information.

V4 processes and stores visual pattern information; as we learn to identify new patterns, neural circuits are formed and strengthened to process those patterns.

The IT cortex processes and stores higher-level cognitive sequencing operations that relate to the sequence of steps to be carried out when performing a visual task (e.g. reading a map).

Cognitive Explanation: The Role of Long-term Memory: Two Types

Explicit Memory

• What can be explicitly recalled.

• Only a little of what is seen makes it in as explicit.

• To be explicitly learned, attentional focus is absolutely necessary.

• To be enduring: (a) a 24-hour consolidation period is essential, and (b) there must be an internal or external consequence attached with a cognitive act. (successful outcome, useful conclusion or reward).

Implicit Memory

• Whatever is retained every time something is seen.

• It is left as a trace.• Very little of this can be

explicitly recalled.• More of what is seen is

stored in implicit memory.

The Entire Process: Beginning to End

Wonderfully described: Pages 118 – 120.

Implications for Design

Make objects easy to identify Use the most typical exemplars of an

object class. Use the angle that is most typical. Use views that show critical

relationships between structural parts. (ambulance)

Make objects novel Novelty holds attention (e.g. gist-object

conflict; visual puzzles)

Implications for Design Make use of well-known symbols

Cases an automatic and rapid activation of the symbol’s associated meaning.

The symbol meaning connection is known as branding.

Be wary of the tension between novelty and branding.

Images should evoke emotion – positive valence; and high arousal. Behavior, however, does not always follow

emotion.