Bruno Laeng

Bruno Laeng

Professor in Cognitive Neuropsychology, University of Oslo, and member of the Centre for Interdisciplinary Studies in Rhythm, Time and Motion (RITMO)
Twitter: @BrunoLaeng

Location Norway


  • A fair comment, thank you. The course's content reflects the fact that several of its teachers are involved in research on music. Your feedback is useful to us: In future editions, we should focus a bit more on medical aspects as well as other issues. The field is already vast and keeps growing.

  • Contact lenses do not seem to create any artifact. At least, I have not seen any report to the contrary.

  • Soon! Sorry, we were all away at a conference but we'll post a video today (I think)

  • Yes, that is the article. We'll add it to the References.

  • Indeed, thank you. It is corrected now.

  • There are heuristics for revealing differences in luminance but it depends on the experiment whether these can be appropriate or sufficient. For example in the case of our study on the 'face race ligthness illusion' (Laeng et al., 2018; doi: 10.1371/journal.pone.0201603) we subtracted two very similar images from one another (Figure 3). These heuristics take...

  • @DougKaro There are several promising developments. I believe one important application is to develop 'inclusive technology' for people who cannot use fingers but can move the eyes. The Skylo ipad is already commercially available. Check this out:

  • @DavidCode In older stationary systems, one would press a key to register the eye position while someone was instructed to look at a fixation cross. This methods is still used with mobile systems. Nowadays, most stationary systems have an automated calibration procedure which registers the eye position when it finds the pupil to be aligned to a predetermined...

  • We often use a chinrest, that can be fastened easily to any table.

  • Good question. There seems to be no study about this and, to my memory, we have not had any participant who had this surgery. My guess, but it is just a guess, is that it should be possible to do normal eye tracking. All I could find is that eye trackers have been used during the surgery itself to improve the operation, see: Lee YC (2007). Active eye-tracking...

  • Thank you. We need this kind of feedback. We kept this section rather basic since we expected a large portion of joiners to be college students but we can see that it attracted also quite a bit of advanced researchers!

  • Yes, a pupil dilation is associated with these emotional responses. It could be because of the increased arousal linked to these states but it could also be beneficial in such states to enlarge the field of vision. Pupil dilation was historically first mentioned in relation to strong emotions (by Charles Darwin, for example). Today, we know that dilations...

  • @MartinPleiß Usually with 'Visual Resolution' is meant the ability to see fine spatial detail. In this case, sympathetic activation causes a loss in visual resolution. What can be gained with pupil dilation is an expansion of the 'functional field of vision' so that more peripheral stimuli can be detected.

  • Good point! And yes, the range of applications is really wide and keeps expanding. There is also a growing number of studies taking an individual differences approach. Here is an example from our lab: Aminihajibashi Hagen Foldal Laeng & Espeseth (2019) 'Individual differences in resting-state pupil size' -

  • As it is typical for academic research, most studies do not have much variation in ages, since participants are recruited among the student population. There are however studies that intentionally include different age groups. Normalization is an approach, but there are other statistical procedures. An interesting article is the following by Piquado and...

  • Thank you. We will tell our friends who made the videos!

  • Yes, it is recommended to do that. On the effect of eye drops on the perception of luminance see also our article: Sulutvedt Zavagno Lubell Leknes deRodez-Benavent & Laeng (2021) Brightness perception changes related to pupil size.

  • The pupil response is driven by the three cones (S, M, L) and the intrinsically photosensitive retinal ganglion cells (ipRGCs). Hence, it is their spectral sensitivities that limit what range of light can affect pupil size (the shortest wavelengths are sensed by S cones and the longest by the L cones, melanopsin's sensitivity lies in between S and M cones).

  • Yes, that is right. The greatest gain is about depth of focus.

  • Just the basics here, indeed, but we hope that it will motivate to look further into the topic...

  • I agree, dyslexia research may benefit from pupillometry and eye tracking. There are already applications in psycho-linguistic research, as it will be discussed later on in this MOOC. You could also check out this reprint, where pupillometry was used in a study of dyslexics:

  • Interesting question. Some studies have used pupillometry during deception. See for example:

  • they should get smaller at the start when you focus, but keep looking and try multiplying two digit numbers (for example, 13 x 14 or 16 x 23).

  • It should be more like a mental calculation. The mirror is just for you to keep track of your own pupils.

  • Good question. I don't know.

  • There are several studies on surprise, perhaps not surprisingly; e.g., Preuschoff Hart & Einhäuser (2011) Pupil dilation signals surprise.

  • Difficult to provide an absolute value that would work for everyone... most cognitive effects are rarely greater than half a millimeter from the resting state, so increases by several mm, without changes in the illumination, would likely signal a high arousal state...

  • Not anymore with the infrared eye trackers! It did matter in the past when pupil diameter/area was calculated directly from the photo image by projecting it and then extracting frame-by-frame the diameters with a ruler. It was harder to do when the contrast was low, as in participants with dark brown irises. In some studies, they recruited exclusively...

  • I like the paper with the parrot! At any rate, mental effort in animals is an understudied topic but there are some interesting studies linking pupil changes to arousal and LC activity (with mice, rats, macaques, chimps). As en example, see: doi: 10.3389/fnins.2014.00100

  • Yes, try that approach

  • Yes, not easy

  • Great!

  • Changes will be small anyhow but larger with increasing difficulty

  • In normal eyes, the changes are consensual, that is light thrown in one eye only causes equal constrictions in both. However, if one uses an eye tracker system that does not compute pupil diameters by taking into account eye positions, then some distortions can exist due to the changes in the orthogonal projection of the pupil when the eye are not aligned to...

  • One can learn some strategies...

  • Increases in luminance are certainly alerting

  • Yes! More on this (about music) in the next weeks...

  • It should work now

  • Agree with Doug

  • Good points. And yes, it could be a case of optimization of vision.

  • Yes, it is possible that the dilation response can be linked to some optimization process of vision. Difficult to prove that it is an 'adaptation' (selected during evolution).

  • Yes it is. It is called the near pupil reflex. Interesting idea about emotional proximity (with a person one empathizes with?)

  • Yes there are variations and we used them for analyzing the fMRI data in the original study (link is above: Alnaes et al.). Note though that the shading around the lines (representing confidence intervals) give a sense of the variability.

  • Correct, changes are small and one needs an eye tracker to see them. Longer recordings show similar curves. There are also studies where measurements is longer than 10 seconds (e.g., minutes, watching a video or listening to music).