The effect of pupil size on grating detection at various contrast levels

doi:10.1016/0042-6989(75)90278-3

Vision Research

Volume 15, Issue 6, June 1975, Pages 645-648

https://doi.org/10.1016/0042-6989(75)90278-3 Get rights and content

Abstract

Resolution to square-wave gratings was measured over a wide range of luminance levels, and a range of size of artificial pupil. Four contrast levels of stimulus were used. The optimum pupil (highest resolution) was found to be close to the size of the natural pupil, at all contrast levels. The consequences of a fixed small or fixed dilated pupil are discussed. The loss of resolution due to a fixed dilated pupil at high light levels is found to be small.

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Cited by (82)

Time-on-task effects on human pupillary and saccadic metrics after theta burst transcranial magnetic stimulation over the frontal eye field
2023, IBRO Neuroscience Reports
Pupil size undergoes constant changes primarily influenced by ambient luminance. These changes are referred to as the pupillary light reflex (PLR), where the pupil transiently constricts in response to light. PLR kinematics provides valuable insights into autonomic nervous system function and have significant clinical applications. Recent research indicates that attention plays a role in modulating the PLR, and the circuit involving the frontal eye field (FEF) and superior colliculus is causally involved in controlling this pupillary modulation. However, there is limited research exploring the role of the human FEF in these pupillary responses, and its impact on PLR metrics remains unexplored. Additionally, although the protocol of continuous theta-burst stimulation (cTBS) is well-established, the period of disruption after cTBS is yet to be examined in pupillary responses. Our study aimed to investigate the effects of FEF cTBS on pupillary and saccadic metrics in relation to time spent performing a task (referred to as time-on-task). We presented a bright stimulus to induce the PLR in visual- and memory-delay saccade tasks following cTBS over the right FEF or vertex. FEF cTBS, compared to vertex cTBS, resulted in decreased baseline pupil size, peak constriction velocities, and amplitude. Furthermore, the time-on-task effects on baseline pupil size, peak amplitude, and peak time differed between the two stimulation conditions. In contrast, the time-on-task effects on saccadic metrics were less pronounced between the two conditions. In summary, our study provides the first evidence that FEF cTBS affects human PLR metrics and that these effects are modulated by time-on-task.
Effects of pupil size as manipulated through ipRGC activation on visual processing
2023, NeuroImage
The size of the eyes’ pupils determines how much light enters the eye and also how well this light is focused. Through this route, pupil size shapes the earliest stages of visual processing. Yet causal effects of pupil size on vision are poorly understood and rarely studied. Here we introduce a new way to manipulate pupil size, which relies on activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) to induce sustained pupil constriction. We report the effects of both experimentally induced and spontaneous changes in pupil size on visual processing as measured through EEG. We compare these to the effects of stimulus intensity and covert visual attention, because previous studies have shown that these factors all have comparable effects on some common measures of early visual processing, such as detection performance and steady-state visual evoked potentials; yet it is still unclear whether these are superficial similarities, or rather whether they reflect similar underlying processes. Using a mix of neural-network decoding, ERP analyses, and time-frequency analyses, we find that induced pupil size, spontaneous pupil size, stimulus intensity, and covert visual attention all affect EEG responses, mainly over occipital and parietal electrodes, but—crucially—that they do so in qualitatively different ways. Induced and spontaneous pupil-size changes mainly modulate activity patterns (but not overall power or intertrial coherence) in the high-frequency beta range; this may reflect an effect of pupil size on oculomotor activity and/ or visual processing. In addition, spontaneous (but not induced) pupil size tends to correlate positively with intertrial coherence in the alpha band; this may reflect a non-causal relationship, mediated by arousal. Taken together, our findings suggest that pupil size has qualitatively different effects on visual processing from stimulus intensity and covert visual attention. This shows that pupil size as manipulated through ipRGC activation strongly affects visual processing, and provides concrete starting points for further study of this important yet understudied earliest stage of visual processing.
Investigating the relationship between background luminance and self-reported valence of auditory stimuli
2022, Acta Psychologica
Citation Excerpt :
As such, our results could also be influenced by dominance, the relationship of which to pupil size has not been systematically explored yet, which future work could endeavour. A general question that arises from this research domain is whether pupil-size adjustments through affective sounds have a functional role, in particular because pupil size can influence detection and discrimination performance (Campbell & Gregory, 1960; Mathôt & Ivanov, 2019; Woodhouse, 1975). The large pupil size in the negative condition may help with increasing visual sensitivity, hence detecting faint stimuli in the environment, which could be survival-relevant.
The present study investigated the effect of background luminance on the self-reported valence ratings of auditory stimuli, as suggested by some earlier work. A secondary aim was to better characterise the effect of auditory valence on pupillary responses, on which the literature is inconsistent. Participants were randomly presented with sounds of different valence categories (negative, neutral, and positive) obtained from the IADS-E database. At the same time, the background luminance of the computer screen (in blue hue) was manipulated across three levels (i.e., low, medium, and high), with pupillometry confirming the expected strong effect of luminance on pupil size. Participants were asked to rate the valence of the presented sound under these different luminance levels. On a behavioural level, we found evidence for an effect of background luminance on the self-reported valence rating, with generally more positive ratings as background luminance increased. Turning to valence effects on pupil size, irrespective of background luminance, interestingly, we observed that pupils were smallest in the positive valence and the largest in negative valence condition, with neutral valence in between. In sum, the present findings provide evidence concerning a relationship between luminance perception (and hence pupil size) and self-reported valence of auditory stimuli, indicating a possible cross-modal interaction of auditory valence processing with completely task-irrelevant visual background luminance. We furthermore discuss the potential for future applications of the current findings in the clinical field.
Human body motion captures visual attention and elicits pupillary dilation
2019, Cognition
Citation Excerpt :
Fluctuations in pupil size also occur as a result of changes in luminance in stimuli (Mathôt, 2018; Woodhouse, 1975). This pupillary light reflex has been suggested to be one of the main confounds in cognitive pupillometry (Sirois & Brisson, 2014; Woodhouse, 1975). Thus, we verified that the luminance levels of both motion categories did not significantly differ from each other.
The social motivation theory proposes that individuals naturally orient their attention to the social world. Research has documented the rewarding value of social stimuli, such as biological motion, to typically developed individuals. Here, we used complementary eye tracking measures to investigate how social motion cues affect attention and arousal. Specifically, we examined whether viewing the human body moving naturally versus mechanically leads to greater attentional engagement and changes in autonomic arousal (as assessed by pupil size measures). Participants completed an attentional disengagement task in two independent experiments, while pupillary responses were recorded. We found that natural, human-like motion produced greater increases in attention and arousal than mechanical motion, whether the moving agent was human or not. These findings contribute an important piece to our understanding of social motivation by demonstrating that human motion is a key social stimulus that engages visual attention and induces autonomic arousal in the viewer.
Small-pupil versus multifocal strategies for expanding depth of focus of presbyopic eyes
2019, Journal of Cataract and Refractive Surgery
Citation Excerpt :
The current modeling shows the familiar reality that expansion of the depth of focus typically is accompanied by a reduction in peak image quality (compare Figure 7 with Figures 8 and 9). Peak image quality was often generated with 2.0 to 3.0 mm pupils47,66,67 and depth of focus typically expanded with pupil diameters of less than 2.0 mm or more than 3.0 mm. The modeling also emphasized that the very different approaches of reducing pupil size or increases spherical aberration are both effective at expanding the depth of focus.
To compare the visually weighted image quality and depth of focus achieved with small-pupil and multifocal strategies for expanding depth of focus of presbyopic or pseudophakic eyes.
School of Optometry, Indiana University, Bloomington, USA.
Computational modeling.
The visual Strehl ratio was computed from monochromatic optical transfer functions over a wide range of primary spherical aberration and defocus levels for pupil diameters ranging from 1.0 mm to 7.0 mm under high photopic light levels (retinal illuminance >900 trolands) and mesopic light levels (2 candelas/m²).
Pupil miosis and added spherical aberration were effective at reducing the impact of spherical defocus. With high light levels at which Weber's law makes neural contrast sensitivity independent of retinal illuminance, small pupils (eg, 1.0 to 3.0 mm) generated higher peak image quality and more effective expansion of depth of focus than the small-pupil multifocal model. However, under low light levels at which the reduced retinal illuminance associated with pupil miosis lowered neural contrast sensitivity, the peak image quality was lower with small pupils (1.0 to 1.5 mm) at all aberration levels. Large pupils and high levels of spherical aberration were most effective at expanding the depth of focus under mesopic light levels.
When reductions in retinal illuminance created by pupil miosis have no effect on neural contrast sensitivity, small pupils produced higher image quality and larger depth of focus than multifocal optics and large pupils. In general, the reverse was true under mesopic light conditions.
Effects of Miosis on the Visual Acuity Space under Varying Conditions of Contrast and Ambient Luminance in Presbyopia
2024, Journal of Clinical Medicine

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¹: Present address: Department of Ophthalmic Optics, UWIST, Cardiff, Wales.

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The effect of pupil size on grating detection at various contrast levels

Abstract

Vision Res.

The behaviour of the pupil during dark adaptation

J. Physiol., Lond.

A retinal acuity direction effect

J. Physiol., Lond.

Optical and retinal factors affecting visual resolution

J. Physiol., Lond.

Effect of size of pupil on visual acuity

Nature, Lond.

Application of Fourier analysis to the visibility of gratings

J. Physiol., Lond