First I want to wish a Happy Mother’s Day to the mothers of all my readers because they obviously raised you well if you’re reading this blog.

I wanted to discuss a scene from one of Eli Roth’s favorite films, Mother’s Day. Apparently his parents were so liberal that they let him show this at his bar mitzvah.

At the other extreme is Roger Ebert who was so repulsed by the film he gave it no stars out of four writing:

During the next 100 minutes or so, the “Mother’s Day” audience witnessed a series of violent events, held together by the flimsiest of stories. The plot: A demented old woman lives in a shack in the woods with her two cretinous sons. Their entertainment is to capture unwary campers and torture, rape and kill them for the delight of their mother. In between, they behave like pigs. A typical dinner scene involves one of the sons shooting a can of pressurized cheese whip down his throat.

The term cretinous seems to be a recent edit in the age of wokenss. Ebert’s book was my cinematic Bible as a kid and I distinctly remember the sons being described as mentally retarded. Indeed that was why I rented the film in the first place. On the other hand long-term memory can often play tricks on us.

But was Ebert (as I recall him) right? Were the sons mentally retarded?

We can answer this question scientifically, because there’s a scene in the film were the mother (who seems like she’d be a HUGE Trump fan) is angry that some of the women they captured escaped. She turns to one of the sons and says:

“Tell your brother Ike that a hound dog that comes home with nothing in his mouth should keep it closed“

The son struggles to repeat this 16 syllable proverb and only manages the first six before being forced to paraphrase. This implies a short-term memory scarcely above that of a three-year-old.

To put this in perspective, on the Sentence Repetition Test norms developed by Carmichael and MacDonald (1984), 12.5-year-olds have a mean of 16.8 with an SD of 3.2. This gives him an IQ equivalent of about 51(Canadian norms, which are like U.S. white norms) however this is an underestimate because he’s a full-grown man not a 12-year-old.

Unfortunately their norms don’t exceed age 12, however looking at the Digit Span norms (a similar test) on the WISC-R and WAIS-R, it seems at the very low end, short-term memory only increases by about 0.33 SD (5 points on the IQ scale) from age 12.5 to young adulthood. Thus his IQ is perhaps 47, putting him in the Trainable (moderate) Retardation range, and what he’s been trained by mother to do is rape and kill.

Of course there’s a lot more to IQ than just short-term memory; indeed as a test of general intelligence, Wechsler called it among the poorest. But Wechsler felt short-term memory was an especially effective test at the low end, famously writing:

Except in cases of special defects or organic disease, adults who cannot retain 5 digits forward and 3 backward will be found, in 9 cases out of 10, to be feeble-minded or mentally disturbed”