Tim Gastrell

On the neural substrates of mind wandering and dynamic thought: A drug and brain stimulation study The impact of mind wandering on our daily lives ranges from diminishing productivity, to facilitating creativity and problem solving. There is evidenc…

My final Registered Report from my PhD is now out in Cortex!
We investigated the role of dopamine & HD-tDCS in mind wandering & sustained attention. While stimulation had no effect, increasing dopamine reduced spontaneous thought and may protect against performance deficits. doi.org/10.1016/j.co...

I really like this paper. I fear that people think the authors are claiming that the brain isn’t predictive though, which this study cannot (and does not) address. As the title says, the data purely show that evoked responses are not necessarily prediction errors, which makes sense!

Well said. Love this take.

Excited to be presenting behavioral and modeling work looking at perceptual decision making under uncertainty with recently learned priors at the EPC/APCV joint meeting today at UNSW, Sydney!

Catch me at 2:45pm in Gallery 1!

@expsyanz.bsky.social

#epc2025

5/5 So the mystery of mechanism remains, but the take home message is this:

Visual awareness is not just about the integration of stimulus history with stimulus content - visual field location matters as well!

OA paper (Gastrell et al., 2025, Journal of Vision): 🔗 doi.org/10.1167/jov....

4/5 Next, we asked whether differences in fixational stability between foveal and peripheral viewing might drive the effect?

In a 4th Exp., we replicated the original effect *again* (so this really IS a thing!), but spatial differences in fixational stability did not correlate either.

3/5 We now knew this was a low-level (spatially specific) effect, so in Exp. 3 we replicated it, and also probed motion adaptation - a likely mechanism.

We found that adaptation to our unambiguous prime generated stronger motion after effects in the periphery, but didn't predict SFM effect! 🤯

2/5 In Exp. 2 we abolished the effect by moving the stimulus between v.f. locations as it changed from unambiguous to ambiguous motion.

This ruled out a high-level (non-retinotopic) visual explanation whereby the influence of a prime on object-level representations might depend on its precision.

1/5 Using unambiguous → ambiguous SFM sequences, we tested whether priming effects on perception of bistable structure from motion vary between fixation and the periphery.

In Exp. 1 we show that immediate perception of a target is more biased towards primes when sequences are fixated v peripheral.

New paper @ JOV!

With Matt Oxner, Frank Schumann and David Carmel.

🧠 Perception of ambiguous motion is shaped by recent visual experience - but does this differ across the visual field?

Yes!

Full open access paper here (Gastrell et al., 2025, Journal of Vision): 🔗 doi.org/10.1167/jov....

🧵

*Please repost* @sjgreenwood.bsky.social and I just launched a new personalized feed (*please pin*) that we hope will become a "must use" for #academicsky. The feed shows posts about papers filtered by *your* follower network. It's become my default Bluesky experience bsky.app/profile/pape...

William James's take on psychophysics is *incredible*. Worth reading the whole quote. #psychSciSky #philsky #VisionScience

"But psychology is passing into a less simple phase. Within a few years what one may call a microscopic psychology has arisen in Germany, carried on by experimental methods,

Out now in AP&P!

Cognitive psych is often traced back to the 1950s.
Psychology is often traced to Wundt's lab in 1879.
Textbooks speak of "proto-psychologists" like Fechner & Helmholtz in the 1800s... Westerners all.

Have you heard about Ibn al-Haytham, whose work predated them by 100s of years?

1/4

Excited to share my first paper: a novel visual illusion discovered by my co-authors Will Turner and Hinze Hogendoorn which we call the "Split-Stimulus Effect", in which a single flashed stimulus is perceived to be in two different locations simultaneously jov.arvojournals.org/article.aspx... [1/5]

A scientific image showing an original image (grayscale dog), the same image after processing with oriented edge filters, and then the spectral power as a function of orientation.

New from my lab: "Priors for natural image statistics inform confidence in perceptual decisions"

We used a natural image statistics approach to investigate the computations underlying perceptual confidence. 🧵

Article: www.sciencedirect.com/science/arti...

PhD student Jesse Gardner-Russell earns $20 an hour. Experts say low pay is turning Australia’s best and brightest away The University of Melbourne student whose work could contribute to curing blindness says ‘people are shocked to find out how unlivable it is’

“The PhD stipend is $33,511 … well below minimum wage of $47,627”

“Universities can raise the stipend to a maximum of $52,352, but a ACGR survey found none have done so. The highest stipend is just over $40,000 … with the average at $34,244.”

#RaiseTheStipend

Prefrontal dimension change-related activation differs for visual search in sparse and dense displays Changes of the target-defining feature dimension have previously been shown to elicit anterior prefrontal activation increases. In the majority of stu…

🖨️ Fresh off the press! www.sciencedirect.com/science/arti...
We have shown that the brain processes visual input differently as a function of display density, violating predictions of dominant cognitive control theories.

Linking neural population formatting to function Animals capable of complex behaviors tend to have more distinct brain areas than simpler organisms, and artificial networks that perform many tasks tend to self-organize into modules (1-3). This sugge...

New results for a new year! “Linking neural population formatting to function” describes our modern take on an old question: how can we understand the contribution of a brain area to behavior?
www.biorxiv.org/content/10.1...
🧠👩🏻‍🔬🧪🧵
#neuroskyence
1/

Conscious awareness, sensory integration, and evidence accumulation in bodily self-perception: http://osf.io/e6tdy/

"The Illusion-Illusion: Vision Language Models See
Illusions Where There are None"

osf.io/preprints/ps...

(this is a more systematic examination of the thing I was looking at a few days ago)

Phase Transition xkcd.com/3025

OK If we are moving to Bluesky I am rescuing my favourite ever twitter thread (Jan 2019).

The renamed:

Bluesky-sized history of neuroscience (biased by my interests)

An absolute pleasure to present some new data at ACNS 2024 in (mostly) sunny Newcastle. Here we showed that human observers judgements of simple motion stimuli broadly follow precision-weighted inference principles. @acnsau.bsky.social