CS 522: Human-Computer Interaction Attention and Mental Workload Dr. Debaleena Chattopadhyay Department of Computer Science debchatt@uic.edu debaleena.com

Attention Attention was of interest around the turn of 20th century. It lost favor during the first half of the 20th century, because it was identified with unseen mental events. How was it restored?

What abilities intrigued them? Applied psychologists in England restored attention as a legitimate research topic. What abilities intrigued them? Air traffic controllers abilities to divide attention among multiple interests. Radar operators ability to maintain vigilance while monitoring screens for enemy subs.

Models of attention Models of Attention Bottleneck Models Resource Models Early Selection Late Selection Single Resource Multiple Resources

Bottleneck model of attention Identifies a stage in the information processing sequence. At that stage the amount of information that can be attended to is limited. FT – promotion of desired stimuli FAT – can be adjusted on the basis of relatively gross physical characteristics: i.e. Spatial location or vocal pitch Allowing only one source of input to enter the identification stage. Here there is a notice of physical features of unattended message speech v non speech male v female voice Semantic features tend to go unnoticed English sentences v jumbled words word meaning, etc. Although again words leak in; a person name is attended to (“cocktail party” effect)

Attentional Filter Stimuli enter a central processing channel one at a time. Filtering of extraneous information happens before identification. Thus, processing of distracters is blocked. Limitations? Leaks are not accounted for.

Attentional Attenuation Early filter serves only to attenuate the signal of an unattended message rather than to block it entirely. Limitations? Not easily testable

Broadbent’s Filter Model

Resource model of attention Views attention as a limited-capacity resource that can be allocated to one or more tasks. Unitary-Resource Models Attention is a single limited capacity resource. It can be applied to various tasks. Performance declines if capacity is exceeded

Unitary-resource model Representative of attentional limitations arising from a limited capacity of resources for mental activity as apposed to focusing on a specific location in the information-processing sequence. Noting that performance suffers when resource demands exceeds the supply. Unitary-resource model

Posner and Boise (1971) RT test results Primary and secondary tasks Where a letter was shown and another letter shown 1 second later, as well audio tones are played. The participant was to determine if the letters where the same or different. Test is setup to determine difficulty of tasks and to predict when operator performance will begin to suffer.

Resource model of attention (cont..) Multiple-Resource Models Distinct subsystems each have their own limited resources. Developed because the performance decrement for multiple tasks often depends on the stimulus modalities and the responses required for each task.

Wickens’ (1984) 3D Model Shows stages of processing (encoding, central, and response), codes (verbal and spatial), input (visual and auditory) and output (manual and vocal) modalities. Assumes two tasks may be performed more efficiently using separate pools of resources. Changes in difficulty in one task should not affect the performance of the other task.

Modes of attention What are the three modes of attention? Selective Divided Arousal and Vigilance

Selective Attention Selective attention is a component of many tasks. One way of attending to visual stimuli is through positioning of the eyes.

Selective attention experiment: Read the bold print. Somewhere Among hidden the in most the spectacular Rocky Mountains cognitive near abilities Central City is Colorado the an ability old to miner select hid one a message box from of another. gold. We Although do several this hundred by people focusing have our looked attention for on it, certain they cues have such not as found type it style.

What can you recall about the sentence?

Results Among the most spectacular cognitive abilities is the ability to select one message from another. We do this by focusing our attention on certain cues such as type style.

What can you recall about the other sentence?

Results Somewhere hidden in the Rocky Mountains near Central City, Colorado, an old miner hid a box of gold. Although several hundred people have looked for it, they have not found it.

https://www.youtube.com/watch?v=vJG698U2Mvo

Change Blindness Change blindness refers to a person’s inability to detect gross or striking changes in a visual scene.

Divided Attention Attending to several sources of input simultaneously Each task does not have to have the same priority.

Arousal and Vigilance Arousal Vigilance Alertness, readiness to respond Arousal influences attentional ability and attentional resources available. Performance deteriorates at high arousal levels. Doing boring tasks for long periods of time lowers arousal. Vigilance Alert watchfulness

The Yerkes–Dodson law (1908)

Mental Workload Assessment What is mental workload? Workload is the total amount of work a person or group is to perform over a given period of time. Mental workload – amount of mental work or effort necessary to perform a task. By what techniques is mental workload assessed?

Mental Workload Assessment Empirical Techniques Primary-task Measures Secondary-task Measures Psychophysiological Measures Subjective Measures

Mental Workload Assessment Empirical Techniques Primary-task Measures Examine the performance of the operator or of the overall system. Secondary-task Measures Workload is assessed by the degree to which performance deteriorates in the dual task situation relative to when each task is performed alone.

Mental Workload Assessment Empirical Techniques Psychophysiological Measures Pupillometry Heart rate Event-related potential (EEG) Limits? Require sophisticated instrumentation May interfere with task performance Subjective Measures Evaluate workload by operator judgment (e.g., NASA-TLX).

Project Discussions

To do: HW 1 DUE – Sep 14 Readings: None Sign up for your proposal presentations – DUE next week Slide credits: K. F. MacDorman, Proctor & Zandt