1
Q
Selection set
A
the visual, auditory, or tactile presentation of all messages, symbols, and codes that are available at one time to a person who relies on AAC
- most systems visual displays of items in the selection set
- may be displayed auditorily (spoken words or messages) or tactually (real, partial objects, textures, shapes, raised dots)
2
Q
How are items in selection set determined?
A
A number of ways
- keyboards: manufacturer assigns symbols to locations
- many systesm: symbols and codes may be preprogrammed by device or application developer, selected on individual basis,
3
Q
Types of select set display
A
- Fixed displays
- Dynamic displays
- Hybrid displays
- Visual Scene displays
4
Q
Fixed displays
A
Any display in which the symbols and items are fixed in a particular location
- Typically low-tech communication boards, some digitized SGD
5
Q
Number of symbols that a fixed display can include is …
A
limited and depends on a person’s visual, tactile, cognitive, and motor capabilities.
6
Q
Fixed display limitations
A
- Protability
- Inefficiency
7
Q
Levels
A
organization of symbol set into pages
8
Q
Dynamic displays
A
Computer screen displays with electronically produced visual symbols that, when activated, automatically change the selection set on the screen to a new set of programmed symbols
9
Q
Hybrid Displays
A
Electronic fixed displays with a dynamic component, such as indicator lights that inform the individual which items in the selection set are available for activation. When one activates the first icon in a sequence, indicators on the display screen light up next to each icon that could be chosen next.
- Designed as a memory aid
- Also displays containing the letters of the alphabet plus word prediction features – letters are fixed, content of word prediction buttons changes with each keystroke
10
Q
Visual Scene Displays
A
Picture, photograph, or virtual environment that depicts and represents a situation, a place, or an experience.
- Individual elements (people, actions, objects) appear within the visual scene and messages are accessed from picture
- Usually employ dynamic displays
-displays selection set within a coherent, integrated visual image
11
Q
Physical characteristics of selection set displays - Number of items
A
Most important factor
- symbols (other than letters or codes): selection set size increases with the number of messages in one-to-one correspondence
- Encoding strategies may decrease number of items in selection set
12
Q
Physical characteristics of selection set displays - Size
A
- Actual size of the symbols or messages on the display determined by visual capabilities, motor access techniques, type of symbol, number of items to display
- Overall size of visual display: compromise among number of items, size of individual items, spacing of items, mounting and portability factors, physical capabilities of the person
- auditory displays: size of display determined by memory and ability to retain organizational scheme of display
- tactile displays: size of set depends on tactile recognition capabilities
13
Q
Physical characteristics of selection set displays - Spacing and Arrangement of Items
A
- Determined largely by visual and motor control capabilities of the individual
- Some people are better able to discriminate among items on display if items are widely separated, surrounded by empty area, if surrounding area is coloured,
- field cuts, blind spots may require irregular spacing arrangements to match visual capabilities
- motor control profile: may have better control of one hand; frequently used items may be displayed to be most accessible to hand with better motor control and with smaller symbols/spacing
14
Q
Physical characteristics of selection set displays - Spacing and Arrangement of Items - Curved array
A
- Designed to accommodate the motor control capabilities of a person using a headstick
- Minimizes forward and backward movements of the head and neck
15
Q
Physical characteristics of selection set displays - Orientation of the display
A
Refers to the position of the display relative to the floor
- Dependent on person’s postural, visual, and motor control capabilities
- Visual and motor capabilities most critical in direct selection display
- Visual and postural factors most critical in scanning selection
- Horizontal floor: provides arm and hand support, stabilization (helpful for weakness, tremor, extraneous movements)
- Requires upright posture
- 30-45 degree angle to floor: compromise for people with physical disabilities; allows to see display while avoiding neck flexion and still providing some hand and arm support for stability
- 45-90 degrees: typically used in combination with light or optical pointers
- care must be taken to not reduce vision
- 90 degree: head or eye tracking strategies
16
Q
Selection techniques
A
The way an individual who relies on AAC system selects or identifies items from the selection set.
17
Q
Selection techniques: Two principal approaches
A
Direct selection
Scanning
18
Q
Direct Selection
A
Person indicates desired item from selection set.
e.g. typing, speech, gestures, manual signing
19
Q
Direct Selection - Options
A
Physical contact
Physical pressure or depression
Pointing (no contact)
Speech recognition
20
Q
Direct Selection - Physical contact
A
- Items are identified from selection set by touching them
Used with many nonelectronic AAC options and mobile technology/tablet computers
21
Q
Direct Selection - Physical Pressure/Depression
A
Activation by depressing a key or pressure-sensitive surface
e. g. standard keyboard, touchpad,
- Pressure typically generated by body part, such as finger, or a body extension (e.g. headstick)
- movement must be sufficiently controllable so only a single item is activated
-pressure thresholds can be adjusted to enhance accurate activation
22
Q
Direct Selection - Pointing
A
- No contact
- Eye pointing, tracking, gazing – one looks at item long enough for communication partner to identify direction of gaze and confirm selected item.
- Often used by young children who have not yet learned other communication techniques, and those with poor positioning, chronic fatigue, or ongoing medical conditions preventing physically demanding options
e. g. Goossens - Pointing without contact, e.g. optical or light-generating (laser-generating) technology mounted on the head
- Technology monitors position of light beam or optical sensor and selects an item if the beam or sensor remains in specific location for a period of time; may also use sonar or infrared technology (head tracker)
23
Q
Direct Selection - Pointing - Motor requirements for optical pointing
A
1/ Ability to direct the light beam to a desired item
2/ Ability to maintain the direction for a prescribed period of time
Must have head control without excessive tremor, extraneous movements
24
Q
Direct Selection - Pointing - Head tracker
A
a sensor (typically sonar or infrared) mounted to forehead or glasses, directed to symbols on screen through fine head movements. Movements control cursor on computer screen to indicate items from selection set
25
Direct Selection - Speech Recognition
Typical speakers, unable t
| t write/control convention computer keyboard.
26
Direct Selection Activation Strategies
When individual uses direct selection to choose an item from an electronic display, they must then activate the item so that the AAC technology recognizes and translate it into usable output.
- Timed activation
- Release activation
- Filtered or Averaged Activation
27
Direct Selection Activation Strategies - Timed activation
- Identify item on display and then sustain contact (dwell) for a predetermined period of time in order for the selection to be recognized
- Most common
- Allows movement across display without activating each item
- Length of dwell time can be adjusted to accommodate individual abilities and situations
- Reduces both inadvertent activations and motor control demands
28
Direct Selection Activation Strategies - Release Activation
- Person contacts display with a finger, retains contact until desired item is located
- Only with displayed controlled by direct physical contact
- Contact time can be adjusted
- Allows individual to use display for hand stability and minimizes errors for those who move too slowly or inefficiently to benefit from timed activation
29
Direct Selection Activation Strategies - Filtered/Averaged Activation
- Technology ignores brief movements away from specific item by sensing amount of time the pointer spends on each item in general area. Device averages accumulated information over short period of time and activates the item that was pointed to longest.
- Facilitators can set amount of time that elapses prior to activation
30
Scanning
- Used for people who are unable to use direct selection
- Items are displayed either by facilitator or electronic technology in a predetermined configuration and the individual must wait while the facilitator or device scans through undesired items before reaching the item of choice.
- Typically access choice using a switch
- Being used less because of head- and eye-tracking access strategies which have a lower cognitive load and learning requirements
31
Scanning - Patterns
Configuration in which items in selection set are presented
- Important that items be identified systematically and predictably
- Circular scanning
- Linear scanning
- Group-item scanning
32
Scanning - Patterns - Circular scanning
- Technology displays individual items in a circle and scans them electronically one at a time until individual stops scanner and selects an item.
- Usually a sweeping hand or individual lights near each item
- Visually demanding
- Relatively easy to master cognitively, may be used with beginning AAC communicators
33
Scanning - Patterns - Linear scanning
Cursor light or arrow moves across each item in the first row, each item in the second row, and each item in subsequent row until item is selected.
- auditory: synthetic voice or human facilitator announces items one at a time
34
Scanning - Patterns - Group-Item Scanning
- Identifying a group of items and then eliminating options gradually until a final selection is made
includes Row-Column Scanning, in which each row on the display is a group. Rows are each highlighted until target is selected, then individual items in that row are highlighted one at a time until the scanning is stopped at the specific item desired.
- group-row-column
35
Scanning - Time and Speed
- Must be personalized according to each individual's physical, visual, and cognitive capabilities
36
Scanning - Selection Control Techniques
Three general selection control techniques are used
- Directed (inverse) Scanning
- Automatic (regular or interrupted) Scanning
- Step Scanning
37
Scanning - Selection Control Techniques - Direct/Inverse Scanning
Indicator or cursor begins to move when the person activates (holds down) a switch of some type. As long as a switch is activated, the indicator moves through the preset scanning pattern.
Selection made when switch is released.
- Useful for people who have difficulty activating switches, but who can sustain activation once it occurs and can release the switch accurately
38
Scanning - Selection Control Techniques - Automatic/Regular/Interrupted Scanning
Movement of indicator or cursor is automatic and continuous, according to preset pattern. Person activates a switch to stop the indicator at the group or item of choice in order to make a selection
- Useful for people who are able to activate a switch accurately but who have difficulty sustaining activation or releasing the switch
- Used when display presentation is auditory
39
Scanning - Selection Control Techniques - Step Scanning
Indicator or cursor moves through a preset selection pattern, one step at a time for each activation of the switch
- Often used by individuals who have severe motor control or cognitive restrictions or who are just beginning to learn to operate electronic scanner s
- Often fatiguing for complex AAC applications
40
Feedback
Two primary purposes of feedback
1/ to let the individual using AAC know that an item has been selected from the selection display (activation feedback)
2/ to provide the individual with information about the message that has been formulated or selected (message feedback)
41
Activation Feeback
The information sent back to the person, upon activation of the input device.
- does not provide information about which symbol or message has been selected
- provides information useful to person operating technology, not to communication partner
- must occur in sensory modality within person's capabilities
auditory: beep, click, sound
visual: light flash, area or symbol flash,
- nonelectronic display: includes seeing one's body part contact the device
tactile : contact with textured surface
- proprioceptive: when pressure is applied against resistant surface (also manual signs, gestures, from position and movement of hands in space)
42
Message feedback
Provides information about the symbol or message itself after it has been formulated.
- May be useful to the communication partner (although secondary importance)
- echo of each letter as it is typed
- screen display of symbols as activated in sequence
- communication partner may produce auditory message feedback (partner reauditorization)
43
Message output
The information that is sent to communication partners
Modes:
- synthetic speech
- print
- gestures
- manual signs
- nonelectronic aided symbols
44
Message input
the information that people who rely on AAC receive from others
- usually takes form of natural speech, gestures, vocalizations, written or printed materials, manual signs
- input mode may be as much of an intervention concern as the output mode by which they send messages.
- - e..g aphasia: may need augmented input in the form of gestures, pictures, or writing in addition to natural speech
45
Synthesized Speech
Types:
- text-to-speech
- digitized speech
Advantages:
1/ may significantly reduce communication partner's burden in interaction
2/ provides information in a mode that is relatively familiar and nonthreatening
3/ allows communication even with communication partners who are not literate and with those who have visual impairments
4/ allows the person using AAC to send messages without first obtaining his or her partner's attention through some other mode
5/ allows communication to occur at a distance
Disadvantages:
1/ Some voices can be difficult to hear and understand in noisy environments, by people with hearing impairments, or by nonnative speakers
46
Synthesized speech - text-to-speech
1/ Text entered into AAC is retrieved from memory as codes and transformed into phonemes and allophones
2/ Device uses stores speech data to generate digital speech signals that correspond to phonetic representations of the text
3/ Device converts digital signals to analog speech waveforms that listeners can interpret and understand
Rule-generated speech -- flexible mathematical algorithm representing rules of pronunciation, pronunciation exceptions, voice inflections, accents.
Diphone-based: diphones extracted from carrier words recorded by natural speakers -- intended to be more natural sounding
47
Synthesized speech - digitized speech
- Waveform coding
- Natural speech that has been recorded, stored, and reproduced.
- Stored in word or message form and must be retrieved as a word or message.
- Cannot be used to convert text into speech
48
Visual Output
- Supportive output method as quality of synthetic speech has improved
- Serves to clarify messages when the listener does not understand synthetic or natural speech
- Important for partners with hearing impairments or unfamiliar with person/device, in noisy environments
49
Visual Output - Hard Copy
- Printer may produce hard copy on paper
50
Visual Output - Computer Screen Messages
Widely used as feedback and output
| - Can manage both orthographic and specialized symbols
51
Visual Output - Unaided Symbols
- Nonelectronic forms of output such as gestures or manual signs impose memory requirements on both of the participants in the communicative exchange
- - no permanent display, all gestures must be produced from memory by sender and processed in memory by receiver (may be difficult with memory impairment)
- - relatively few people are likely to understand
52
Visual Output - Aided Symbol Displays
- In nonelectronic applications that use aided symbols, communication partners interact directly with the symbol set itself.
- To maximize intelligibility, simultaneous written translations are often used
- Must get person's attention, partner must be able to turn or move toward individual using AAC to see board, and partner must possess sufficient sensory acuity to see output
53
Visual Input
Appears to facilitate receptive language comprehension for some individuals, e.g. people with ASD.
54
Visual Input - Unaided symbols
Gestures and signs
- require no additional paraphernalia, always available for use
- often used in total communication paradigm (communication partners tend to slow speaking and signing rates, insert more pauses) --> expressive and receptive language gains
55
Visual Input - Aided symbols
Drawing simple pictures, writing letters and words while speaking to help with comprehension of messages.
- Aided language stimulation
- - facilitators must prepare activity boards with necessary symbols in advance and have them available when needed
- System for Augmenting Language
- Facilitator points to key symbols while speaking, in a manner parallel to that used in total communication
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Augmentative & Alternative Communication
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