I sampled a bunch of pop-sci books on the effects of technology on the mind. Most were shallow and anecdote-heavy. This one proposes a concrete mechanism governing behavioural changes and puts in the context of current understanding of cognitive control. Everything in these notes appears to be pretty well supported by both correlational studies and controlled interventions. Not one of those books that weaves a beautiful story out of a single crappy experiment.

Both authors are professors researching this topic. First author founded a neuro-therapy company.

Executive function

Two main sources of behaviour. Seems to map roughly to dual process theory? Bottom-up - perception-action cycle. Top-down - goal creation and enactment.

Different strengths and weaknesses, not clear which system should have control. Eg trying to concentrate on a problem while being distracted by traffic noises vs trying to concentrate on a problem while ignoring the oncoming car.

Conflict between the two is mediated by executive functions. Main components are working memory, goal management and attention.

Working memory. Maintain internal representations and perform operations on them. Bridge - allows longer delays in perception-action cycle. Eg recalling last observed position of predator, plotting their possible movements, planning a course around.

Goal management. Scheduling both internal and external behaviour. Directing mental resources. Task-switching, including hierarchies of sub-tasks for complex behavior. Multi-tasking at this level is not possible - executive functions are single-threaded - rapid task-switching instead.

Attention. Complex, not well-understood. Spotlight. Focus on specific signal/pattern, area, moment in time etc eg throw a stone and watch for movement in the long grass when it lands. Ignore/suppress irrelevant stimuli. Focus can be spatial, temporal, specific pattern etc. Explains suppression as a way to conserve resources for more important tasks, but later mentions that suppression is cognitively demanding. ‘Resources’ is vague. It’s not at all clear to me right now how focusing and ignoring work. Setting priors for pattern recogntion? Discarding unimportant signals earlier in the pipeline? Suppressing the results of processing from intruding on working memory? Focusing and ignoring appear to be different processes, can fail independently eg ignoring decays much faster with old age.

Interference. Internal vs external eg decide to check email vs hearing notification. Distraction (resisted) vs interruption (endorsed) eg hearing notification and ignoring vs hearing notification and checking.

Bottom-up processing prioritizes by novelty and saliency (where saliency can depend on learned associations). Can top-down processing prime saliency?

Many limits on executive function.


Working memory:

Goal management:

Executive functions follow a U-shaped curve peaking at 20-25yo. But doesn’t mention any longitudinal experiments - could be generational effects too? Also not clear how much is physical degradation vs disuse.

Sleep deprivation has huge impacts on executive function.


Time to 50m users:

Uptake of new tech is accelerating.

Not sure it makes sense to compare angry birds to tv rather than eg a particular tv show, but general point seems sound.

Huge increase in frequency and range of tech use. Numbers highest in younger generations. Again no longitidunal, but seems likely.

Lots of studies to set the scene. I’ll just note a few interesting examples:

Performance degradation is higher for social media and messaging than for other tech. Hypothesis - social interaction is a much stronger attentional priority than entertainment - matter of survival.


This section seems out of place, but still interesting.

ADHD sufferers switch tasks slower and have poorer working memory.

Symptoms of anxiety disorders correlate with tech use.

Depression not clear eg sometimes social media use ~ with reduced depression. Support network?

ASD sufferers struggle with planning flexibility and inhibition of irrelevant stimulus.


Why interrupt ourselves, especially when we know the costs and we are trying to focus? How might tech exacerbate self-interruption?

Optimal foraging. Mariginal Value Theorem. Explore vs exploit - switch resources when predicted value of new resource outweighs switching costs. Accurate predictions of foraging behaviour in several animal species.

Information foraging. MVT has been applied to browsing patterns. Perhaps can explain self-interruption too?

Resource intake curve is an internal estimate. Might be moved around by:

Actual evidence for these seems a little weak, but at least it’s a concrete model.

Improving executive function

Rates strength of evidence as prescriptive, signal or plausible.




Interest in cross-modal ‘Body-Brain trainer’.

No guarantee that any of these improvements will transfer to real-world behaviour.

Diet? Sleep?

Changing behaviour

Pretty typical recommendations eg leave phone in a drawer while working.

Improve meta-cognition by exposure to multitasking tests and the data in this book. Also by self-recording?


Enjoyable, but I wish it had been more in-depth.