You stop short in the middle of a sentence. Your eyes shift. You can practically feel your mind twisting, as it tries to wring out the word resting just behind your lips — but nothing springs to mind. While this tip-of-the-tongue phenomenon happens to just about everyone from time to time, rarely does it become a serious problem. But this is not always the case.
Over at Not Exactly Rocket Science, Ed Yong describes the results of some fascinating research involving a British family (known only as "JR") whose members commonly struggle with what linguists call "semantic cognition," the ability to link words with meaning. The researchers have shown, for example, that no fewer than eight JR family members, spanning four generations, struggle with semantic cognition, suggesting the problem has a strong genetic component.
We've included an excerpt here, but you'll definitely want to check out the rest; it's an absolutely fascinating read.
David Skuse from University College London first met the JR clan when one of their members– a six-year-old boy – was referred to his clinic at Great Ormond Street Hospital because of problems with remembering words. Skuse realised that the boy's mother shared the same problem, and both she and her son used stock answers to divert attention from their difficulty. She, for example, would say that she couldn't remember the English version of a word, even though she was a native English speaker.
Skuse probed further, and found that many members of the extended family, across four generations, have the same problem. "This illustrates how interesting new findings sometimes crop up unexpectedly," says Dorothy Bishop, who studies language impairments at the University of Oxford and has worked with Skuse before. "The intriguing pattern of deficits in this family could easily have been missed, because the problems are rather subtle and don't fall into any pre-existing category of developmental learning difficulty."
Bishop adds, "I suspect that many clinicians seeing such a child would end up diagnosing autism spectrum disorder and would not pick up on the memory difficulties. Several affected family members were described as shy, withdrawn, or poor at socialising, yet these problems appear to be secondary to the verbal memory problem, rather than evidence of a core autistic deficit."
Skuse's team, including Josie Briscoe and Rebecca Chilvers, have been working with the JR family ever since to understand the nature of their difficulty. They interviewed and tested all the affected family members. About half of them share the same problems, which develop from an early age and don't get progressively worse. This suggests that a dominant gene is involved – a single copy can cause the full suite of problems.
Continue reading at Not Exactly Rocket Science.