Mean Blink Research Articles

Increased blink rate in adolescent patients with psychosis

Increased blink rate, a putative correlate of central dopaminergic activity, may be elevated in patients with chronic schizophrenia. In an effort to determine whether this elevation is due to iatrogenic factors, blinking was examined in medication-naive adolescent psychiatric inpatients undergoing their first hospitalization. The mean (±SD) blink rate of patients with psychosis ( n = 13, 16 ± 9 blinks/minute) was significantly greater than that of the nonpsychotic control inpatients ( n = 35, 10 ± 6 blinks/minute). Thus, elevated blink rate may be a feature of psychosis that is not necessarily caused by neuroleptic treatment or psychiatric hospitalization.

Spontaneous Blink Rates of Birds

The blinking activity of birds has received little attention in the scientific literature, although the subject has been studied in more depth in mammals (Wood and Saunders 1962, Zametkin et al. 1979). Mammals have characteristic species-specific blink rates that are independent of light, heat, or humidity (Blount 1927, Ponder and Kennedy 1928). They range in frequency from 0-4/min in the rat, mouse, hamster, and fox, to 8-22/min in primates, to 3036/min in the domestic pig (Hall 1945, Stevens and Livermore 1978). Moreover, the blink rate of diurnally active mammals is moie than 10 times higher than that of nocturnally active species. In this study, we measured the spontaneous blink rates of 25 species of birds and examined them for similar diurnal/nocturnal patterns. Accurate data on blink rate could provide a way of assessing the physiological condition of individual birds. Alternatively, if such rates increase with age as they do in humans (Zametkin et al. 1979), blinking may provide an estimate of age, much as external morphological features are used in certain species. We determined the spontaneous blink rates of 25 species of birds in zoos and bird sanctuaries (Table 1). Our measurements were made between 09:00 and 15:00 generally in daylight, but in fluorescent dim blue light in the case of the Screech Owl. Observations were made either at close range or with a spotting scope. After the bird had habituated to us (1-5 min), we counted the number of times that it blinked in 10 separate 1-min periods while it sat quietly. For most species, we used at least two individuals to determine a mean blink rate. Both bilateral and unilateral blinks as well as closure of the nictitating membrane were counted, but are not distinguished in this report. The blink rates of most individuals and species were relatively constant under quiet, unchanging test conditions. Mean values ranged from 1.5/min for the Screech Owl to more than 50/min for the Rock Dove and Rubythroated Hummingbird. In several species, including the Whi e-winged Dove, Wild Turkey, and Rock Dove, blinking appeared to be correlated with head movement, suggesting that the vestibular apparatus modulates the blink reflex in these birds, as has been reported in humans (Ponder and Kennedy 1928). Although we did not control the amount of light to which the birds were exposed, the blink rates differed little between individuals in bright light and those in the shade. I deed, a blind Screech Owl blinked at a mean rate (1.2 blinks/min) that did not differ significantly from that of conspecifics with normal vision (1.5 blinks/min). This obs rvation suggests that in birds, as in humans, the blink ate for individual species does not depend upon photostimulation of the retina, provided the light to which subjects re exposed is not extremely bright. Our results also suggest that diurnally active birds blink more freque tly than nocturnally active species (Table 1). In g neral, all species of owls blinked less than 10 times per minute, whereas diurnal species had higher mean rates. The Snowy Owl, which is active in daytime, had the highest rate among the owls. Diurnal m mmals also have considerably higher blink rates than nocturnal mammals; furthermore, their rapid

Spontaneous eye-blink rates and dopaminergic systems.

A series of studies demonstrated a possible relationship between eye-blink rate and central dopamine activity. First, apomorphine and other dopamine agonists acutely increased blink rate in monkeys, an effect blocked by sulpiride. Secondly, parkinsonian patients with levodopa-induced dyskinesia exhibited twice the mean blink rate (21 blinks/min) of other parkinsonians (11 blinks/min, P less than 0.002) whereas the more symptomatic of the nondyskinetic patients had a very slow rate (3 blinks/min, P less than 0.01). Thirdly, schizophrenic patients had an elevated mean blink (31 vs 23 blinks/min for normals, P less than 0.05) which was normalized by neuroleptic treatment. Thus, the correlation with central dopamine activity may also prove clinically useful in selected neuropsychiatric disorders.

Blink rates in parkinsonism

AbstractSpontaneous eye blink rates were counted in 54 parkinsonian patients, 52 of whom were receiving levodopa. The mean blink rate of the more disabled patients, 7 per minute, was significantly less than the 17 blinks per minute observed in midly disabled (p < 0.02) and 22 blinks per minute (p < 0.001) in moderately disabled patients. Drug‐induced dyskinesia in 21 patients was associated with an elevated blink rate, 32 per minute, as compared with 12 per minute for non‐dyskinetic patients (p < 0.01).

The nature of normal blinking patterns.

The blinking patterns of 20 normal subjects were examined under controlled experimental conditions. While the mean blink rate was 12.55 blinks/min, there were marked variations between individuals. As well, each subject displayed a characteristic pattern of blinking, mixing inter-blink periods of shorter and longer durations in a regular fashion.

Speaking, thinking, and blinking

The effect of several mental tasks on the spontaneous eye blink rate in 36 normals was examined. The blink rate during silence was 19.0 blinks/ minute. This was significantly lower than the mean blink rate during speech (24.7 blinks/minute) and while listening to a paragraph to be memorized (27.6 blinks/ minute). Reading reduced the blink rate to 12.3 blinks/ minute. Men were more able to suppress and speed up blinking than women.

Oculomotor signs in a psychiatric population: a preliminary report.

Oculomotor signs were evaluated in 172 psychiatric patients. Schizophrenic patients demonstrated a significantly higher incidence of staring, pursuit breaks, and lateral glances than did controls or other psychiatric patients. Oculomotor signs may help to differentiate schizophrenia from affective and nonpsychotic disorders. Patients with tardive dyskinesia and patients treated with tricyclic antidepressants demonstrated a significant elevation in mean blink rate. Elevated blink rates may be on early indicator of tardive dyskinesia.

Ocular movements and spontaneous blink rate as functions of personality.

Although the importance of both deliberate and spontaneous blinking and eye movements in the study of certain perceptual phenomena has been stressed repeatedly, the circumstances surrounding the relative contributions for these two variables remain open to question. The Merediths (1962) suggested that differential eye movements and blink rates may be associated with different types of viewing instructions. This could partially account for recently reported differences among Necker cube fluctuation data obtained under different viewing instructions (Franks & Lindahl, 1963). In this study, in which eye movements per se were not investigated, blinking was unrelated either to extraversion or to fluctuation. In a subsequent invesrrg3rron eye movemenrs and blink rates were related ro the extraversion scores of 39 normal adult males. Spontaneous blinking was recorded photoelectrically while Ss sat in a sound proof room gazing at a 600-rpm rotating spiral for rare I-min, viewing periods, separated by a 3-min. interval. Extraversion scores were then obtained by having Ss complete the E scale of the Maudsley Personality Inventory ( M P I ) . Spontaneous eye movements were investigated by a technique which required Ss to keep their heads still and report any fleering obtruding upon the otherwise uniform grey appearance at the same high speed (Holland, 1960) . This effect, which also occurs when certain blinks occur, is supposed to be stable and reliable. After a brief explanation and practice period Ss were given rwo trials of 1 min. separated by a 3-min. interval, all flashes being recorded by a light touch on a silent telegraph key attached to a counter. For 2 0 Ss the blink test followed the questionnaire. The order of presentation was found to produce no pertinent differences in either rate of blinking or report of flashes. Pearson product-moment testretest correlations were .72 and .84 for the blinks and flashes, respectively. Correlations among mean blink rate, mean flash rate and E were as follows: blink-E, r = .lo; blink-flash, I = .22; E-flash, r = .42. If flash rate does indeed measure certain eye movements, then these data suggest that eye movements may be of greater pertinence than eye blinks in studies involving visuaI fixation and extraversion. These data also provide some support for Eysenck's contention that extraverts are poorer at. visual fixation than are introverts (see Holland, 1960).