Kim S Landzberg | PubMed Health

PubMed2004

Substrates of negative accommodation.

Negative accommodation refers to a unique phenomenon, sparsely documented in rare individuals, whereby evanescent increases in vision (described as "flashes" of clear vision) accompany a decrease in the overall plus power of the eye. Complementing less than a handful of dated studies, a few recent personal communications from eye care clinicians claim to have objectively assessed negative accommodation (e.g., by retinoscopy). Whereas negative accommodation may explain informal accounts claiming occasional improved visual acuity in uncorrected myopes, its mode of operation is not established. We sketch a potential mechanism by which negative accommodation may operate, if it exists.

Accommodation, Ocular↗

PubMed2003

Posthypnotic suggestion and the modulation of Stroop interference under cycloplegia.

Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly suggestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation (e.g., visual blurring or looking away) could account for this finding. Using cyclopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Although visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroop interference is neither robust nor inevitable and support the hypothesis that posthypnotic suggestion may exert a top-down influence on neural processing.

Adult↗