The effects of age and cognitive load on peripheral-detection performance.

Age-related declines in both peripheral vision and cognitive resources could contribute to the increased crash risk of older drivers. However, it is unclear whether increases in age and cognitive load result in equal detriments to detection rates across all peripheral target eccentricities (general interference effect) or whether these detriments become greater with increasing eccentricity (tunnel effect). In the current study we investigated the effects of age and cognitive load on the detection of peripheral motorcycle targets (at 5°-30° eccentricity) in static images of intersections. We used a dual-task paradigm in which cognitive load was manipulated without changing the complexity of the central (foveal) visual stimulus. Each image was displayed briefly (250 ms) to prevent eye movements. When no cognitive load was present, age resulted in a tunnel effect; however, when cognitive load was high, age resulted in a general interference effect. These findings suggest that tunnel and general interference effects can co-occur and that the predominant effect varies with the level of demand placed on participants' resources. High cognitive load had a general interference effect in both age groups, but the effect attenuated at large target eccentricities (opposite of a tunnel effect). Low cognitive load had a general interference effect in the older but not the younger group, impairing detection of motorcycle targets even at 5° eccentricity, which could present an imminent collision risk in real driving.

Evaluation of a Paradigm to Investigate Detection of Road Hazards when Using a Bioptic Telescope.

SIGNIFICANCE: A new driving simulator paradigm was developed and evaluated that will enable future investigations of the effects of the ring scotoma in bioptic drivers with diverse vision impairments and different telescope designs. PURPOSE: The ring scotoma may impair detection of peripheral hazards when viewing through a bioptic telescope. To investigate this question, we developed and tested a sign-reading and pedestrian-detection paradigm in a driving simulator. METHODS: Twelve normally sighted subjects with simulated acuity loss (median 20/120) used a 3.0× monocular bioptic to read 36 road signs while driving in a simulator. Thirteen of 21 pedestrian hazards appeared and ran on the road for 1 second within the ring scotoma while participants were reading signs through the bioptic. Head movements were analyzed to determine whether the pedestrian appeared before or only while using the bioptic. Six subjects viewed binocularly, and six viewed monocularly (fellow eye patched). Two patients with real visual acuity loss in one eye and no light perception in the other performed the same tasks using their own telescopes. RESULTS: For the monocular simulated acuity loss group, detection rates were significantly higher when the pedestrian appeared before using the bioptic than when it appeared while using the bioptic and was likely within the area of the ring scotoma (77% vs. 28%, P < .001). For the binocular simulated acuity loss group, there was no significant difference in detection rates for pedestrians that appeared before or while using the bioptic (80% vs. 91%, P = .20). The two monocular patients detected only 17% of pedestrians that appeared while looking through the bioptic. CONCLUSIONS: Our results confirm the utility of the testing paradigm and suggest that the fellow eye of normally sighted observers with simulated acuity loss was able to compensate for the ring scotoma when using a monocular bioptic telescope in a realistic driving task.

The Effects of Age and Central Field Loss on Head Scanning and Detection at Intersections.

PURPOSE: Using a driving simulator, we quantified the effects of age and central field loss (CFL) on head scanning when approaching an intersection and investigated the role of inadequate head scanning in detection failures. METHODS: Participants with CFL (n = 20) and with normal vision (NV; n = 29), middle-aged (36-60 years) or older (67-87 years), drove along city routes with multiple intersections while head movements were recorded. The effects of age and CFL on scanning were analyzed at 32 intersections with stop/yield signs. The relationships between age, CFL, scanning, and detection were examined at four additional intersections with a pedestrian appearing on the far left. RESULTS: Older NV participants made fewer total scans than middle-aged NV participants and had smaller maximum scan magnitudes. Head scanning of older CFL and NV participants did not differ, but middle-aged CFL participants made fewer head scans, had higher rates of failing to scan, and made smaller head scans than middle-aged NV participants. For the older NV and both CFL groups, detection failures were high (≥58%); head scan magnitudes were 15° smaller when the pedestrian was not detected than when it was detected. CONCLUSIONS: Both older NV and CFL participants exhibited head scanning deficits relative to middle-aged NV participants. Unexpectedly, however, it was the middle-aged CFL group that performed least well when scanning, a finding that warrants further investigation. TRANSLATIONAL RELEVANCE: Failing to head scan sufficiently far at intersections may place older drivers and drivers with vision impairment at a higher risk for causing collisions.

THE EFFECTS OF GUIDANCE METHOD ON DETECTION AND SCANNING AT INTERSECTIONS - A PILOT STUDY.

Older drivers are frequently involved in collisions at intersections. One reason may be inadequate head and eye scanning when approaching the intersection. Prior driving simulator research on scanning at intersections has employed two main methods to guide subjects through the simulated world: auditory instructions similar to GPS navigation and following a lead vehicle. However, these two methods may have differing effects on head and eye scanning behaviors. We therefore conducted a pilot study to assess the effects of guidance method on participants' head and eye movements as well as their detection of motorcycle hazards at intersections. Detection rates were significantly higher when following a lead vehicle than when following GPS instructions, but participants were closer to the intersection when they responded. Preliminary examination of the head and eye movement data suggests participants scanned less frequently when following the lead vehicle.