Random-dot Kinematograms

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Random-dot Kinematograms

Basic Characteristics

  • Description

Random dot kinematograms (RDK), where the percentage of dots that move together in the same direction, as if attached to a flat, rigid surface, is varied while the remaining dots move randomly across trials, is the most commonly used measurement of motion coherence thresholds. It requires global integration of motion across several points. The motion coherence thresholds are determined by measuring the percentage of coherently moving dots required for accurate detection of coherent motion or for direction discrimination. Each dot has a limited lifetime so that the detection and interpretation of coherent motion requires a global integration of multiple motion signals. Participants report with a button press whether motion is in one direction or another (left or right; up or down) or which sub-regions contains coherent motion. The perceived coherence is directly related to activity in area MT, but not to activity in earlier visual areas and to date, no study has addressed the neural areas involved in visual perception of motion in observers with ASD.

  • RDK in ASD populations

One study demonstrated that children with ASD have higher motion coherence thresholds across three trials relative to typical children (over 45% higher). This means that ASD children need a higher percentage of coherently moving dots to detect a coherent direction in motion movement. Static form coherence thresholds were not elevated in these same children; thus, it was concluded that motion perception is compromised in ASD, possibly through dorsal stream deficiencies. More recent evidence has indicated deficits in static form coherence thresholds raising the possibility of ventral stream deficiencies as well. Using a simplified RDK, one study showed a mean motion coherence threshold of about 25% in high-functioning children with ASD compared to 15.3% in typically developing children. Another laboratory found that children with ASD required an average of 22.4% of the dots to translate coherency, whereas controlled required 11.1% to discriminate global direction. Similar patterns were reported when RDK were displayed for 1 second, correlations with autistic traits vs. motion coherence thresholds, and with those with high-functioning autism, but not AS with Glass patterns (randomized dot arrays depicting correlated dot pair).

A landmark study compared ASD and control observers viewing two classes of stimuli luminance defined and contrast defined undergoing three categories of motion (translation, rotation, and radial motion). The stimuli consisted of superimposed noise upon sinusoidally modulated gratings. The perception of global direction in both of these stimulus types required a global integration of motion signals. However, contrast defined stimuli differ from luminance defined stimuli in several ways, such that they produce weaker motion aftereffects, are more attention dependent, and can require longer periods of temporal integration than luminance defined stimuli. Contradictory to previous studies, there was no performance differences found between those with and without ASD in attempting to discriminate two directions of motion with the luminance defined stimuli. There were deficits in motion perfection with the contrast defined stimuli in observers with ASD, such that observers with ASD demonstrated less perceptual sensitivity in the direction discrimination task compared to controls. It was concluded that deficits in visual motion processing in relation to ASD are specific to the perception of complex motion or second-order motion, and is most apparent when observers are 6 years of age or younger. Similarly, several studies found no significant difference in motion coherence thresholds between observers with ASD and matched control observers using RDKs. Studies indicate that some adults on the autism spectrum either achieve visual motion sensitivity comparable to typically developing individuals or they develop compensatory mechanisms to allow them to perform as well. Thus while children with ASD display deficits in these tasks, the deficits can disappear by adulthood.

    • Ocular flow

Evidence suggests that children and young adults with AS differ in their postural responses to optic flow compared to those with ASD. Children and adults with AS do not exhibit decrements in motion coherence or form detection thresholds when observing locally oriented Glass patterns, but children and adults with HFA do.

Researchers originally interpreted that damage to the dorsal pathway resulted in atypicalities in visual sensitivity to coherent motion, and area MT, which receives substantial input from the magnocellular pathway, is essential for the detection of motion. However, no study to date has examined the neural activity in observers with ASD during the perception of RDKs. The relationship between dorsal pathway function and ASD becomes unclear when the data across experiments is aggregated. Thus, some studies, but not all, support the hypothesis that motion perception by observers with ASD can be fully understood as reflecting an automatic default of local motion processes, as a result of some dysfunction in the dorsal stream. Another neurophysiological model suggests that the superior temporal sulcus (STS) dysfunction, which is compromised in those with ASD, mildly sensitive to RDKs, strongly responsive to PLDs of human movement and social action, and shows more activity during the perception of second-order rather than first-order motion, is responsible for the ambiguous motion coherence results across studies.





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  • References


Related Information

  • Cognitive construct associated with this task (vote for your favorite, or nominate a new construct label by editing this page):
  • Indicators (dependent variables, conditions, or contrasts; measurement variables used for analysis) associated with this task (vote or nominate by editing this page):
    • dependent variables:
  • Closely related pages (vote or nominate related pages by editing this page):
    • Within Species
    • Across Species
  • CNP Level
  • Primary Species

External Resources

  • Database links

Task Details

  • Task Structure (please given an overview of the task procedures here [i.e., overall design, block, trial, and within-trial event structure and timing])
    • procedure
      • block: experimental block administered until 30 trials were completed
      • trial: 30 completed trials
  • Stimulus Characteristics
    • sensory modality (e.g., visual, auditory, somatosensory, gustatory, olfactory): visual and auditory
    • functional modality (e.g., linguistic, spatial, numerical, categorical):
    • presentation modality (e.g., human examiner, paper, computer display, headphones, speaker): computer display with speakers
  • Response Characteristics
    • response required -
      • effector modality (e.g., vocal, manual, pedal): manual
      • functional modality (e.g., words, drawing, writing, keypress, movement): mouse press
    • response options (e.g., yes/no, go/no-go, forced choice, multiple choice [specify n of options], free response)- collect money or pump balloon
    • response collection (e.g., examiner notes, keyboard, keypad, mouse, voice key, button press)- mouse
  • Assessment/Control Characteristics
    • timing
      • monthly cycle dependent??
      • circadian dependent??
    • control assessment
      • 5 senses??
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