Altered gait parameters in distracted walking: a bio-evolutionary and prognostic health perspective on passive listening and active responding during cell phone use

The underpinnings of bipedal gait are reviewed from an evolutionary biology and prognostic health perspective to better understand issues and concerns related to cell phone use during ambulation and under conditions of distraction and interference. We also consider gait-related health issues associated with the fear of or risk of falling and include prognostic dimensions associated with cognitive decline, dementia, and mortality. Data were acquired on 21 healthy young adults without hearing loss, vestibular, balance, otological or neurological dysfunction using a computerized walkway (GAITRite® Walkway System) combined with specialized software algorithms to extract gait parameters. Four experimental conditions and seven temporo-spatial gait parameters were studied: gait velocity, cadence, stride length, ambulatory time, single-support time, double-support time, and step count. Significant main effects were observed for ambulation time, velocity, stride velocity, and double-support time. The greatest impact of distraction and interference occurred during the texting condition, although other significant effects occurred when participants were verbally responding to queries and passively listening to a story. These experimental observations show that relatively simple distraction and interference tasks implemented through the auditory sensory modality can induce significant perturbations in gait while individuals were ambulating and using a cell phone. Herein, emphasis is placed on the use of quantifiable gait parameters in medical, psychological, and audiological examinations to serve as a foundation for identifying and potentially averting gait-related disturbances

Some poststimulatory effects in the acoustic stapedius reflex: Monotic and dichotic stimulation

Two experiments were performed to study short-term poststimulatory effects in the acoustic stapedius reflex in five normal-hearing volunteers. In Experiment 1, monotic magnitude-intensity functions (MIFs) were obtained for a 20-ms test stimulus preceded by a conditioning stimulus varying in duration (20, 50, 100, 500 ms) and level ($-10$, 0, $+10$ dB re: stapedius-reflex threshold). The conditioner and test stimuli were separated by various interstimulus intervals (0, 20, 50, 100, 500 ms). Experiment 2 was similar in design except that fewer interstimulus intervals were used and stimulus presentation was dichotic. Both experiments demonstrated that a prior conditioning stimulus produced significant increases in stapedius-reflex response magnitude. These poststimulatory increases in stapedius-reflex magnitude were characterized by complex interactions among stimulus variables with similar interactions occurring for both monotic and dichotic stimuli. A simple superposition effect of the responses to the conditioner and test stimulus does not account for the effect of prior stimulation since substantial increases in test-stimulus magnitude persisted after the decay of the conditioner response. These data suggest that the major effect of prior stimulation on stapedius-reflex magnitude occurs central to the first-order neuron in the stapedius-reflex arc