I found the following article to be incredibly fascinating, and concur with study author Jennifer M. Sumner’s statement that hoarders have difficulties with establishing bulk categories for their possessions. This results in a complete inability to organize items, so they accumulate. I have included a link to the original post for reference.

https://www.braindecoder.com/inside-the-mind-of-a-hoarder-1378787672.html

Inside the Mind of a Hoarder
A new study hints at the real reason behind the mess.
By Agata Blaszczak Boxe

When Paul Hammond, a resident of Mobile, Alabama, started collecting used cars and appliances to sell for scrap metal, he probably did not suspect that his habit would one day turn into a serious hoarding issue and land him in jail.

But, over the years, random items kept piling up in his yard, and Hammond just was not getting rid of them. After numerous complaints from the neighbors, who accused him of turning his property into a junkyard, county authorities got involved and cited him for criminal littering. They also threatened to put him in jail if he did not clean up.

When Hammond’s brother came to visit him for the Fourth of July several years ago, he saw about 90 cars, about 50 refrigerators and 100 lawn mowers in the yard. The brother quit his job for four months to help Hammond get rid of the stuff. But the county officials were not happy with the job the men did and they put Hammond in jail for five days.

“I thought I was a law-abiding citizen,” Hammond told A&E’s show Hoarders. Although he was released after the five days, he was still facing up to 90 more days in jail if he did not clean up around the time the TV crew came to film an episode about him.

Hammond is one of the many people with hoarding disorder who end up being overwhelmed with possessions they can’t organize or get rid of. Hoarding is a disorder that may be present on its own or as a symptom of another disorder, for example, obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder (ADHD) and depression. To try to understand what mechanisms in the brain may be responsible for hoarding behavior, researchers have recently begun to look at the neurocognitive aspects of the disorder, but studies have yielded mixed results.

For example, one study looked at people with obsessive-compulsive disorder and found that those who had high levels of hoarding behavior performed significantly worse on tests of decision making, planning and properly shifting attention, compared with people with OCD with lower levels of hoarding. However, it’s difficult to conclude that these cognitive traits are responsible for hoarding because another study found people with hoarding disorder actually performed better on the same type of test than participants with non-hoarding OCD.

In a new study, published in Neuropsychology, researchers looked at neurocognitive functioning in 26 people with hoarding disorder and 23 people without the disorder. The researchers thought the discrepancies between the results of previous studies could have been caused by the effects of medications used by some of the participants, so in the new study, they decided to only include people who were not taking any medication that could affect their brain functioning in any way.

The new study found no significant differences in how people in both groups performed on tests examining their verbal memory, attention, or executive functions such as planning, organization and decision-making.

But the researchers did find a difference between the groups: when they asked the participants to categorize different stimuli in a separate test, the people with the hoarding disorder appeared to use different learning strategies during the categorizing task, compared with the controls. Namely, they tended to use explicit learning, which is about developing and verbalizing rules to remember something, explained study author Jennifer M. Sumner, of the University of California San Diego School of Medicine. In contrast, most people without the disorder used implicit learning, which is an unconscious, non-linear and non-verbal way to learn new information.

The researchers don’t know for sure how these results should be interpreted. But the findings do make them wonder whether, in people with hoarding disorder, the inability to organize and sort through their possessions might have something to do with how they process information, Sumner said.

It could be, for example, that people with the disorder try to come up with rules as to where different objects should go, but because they may end up creating too many rules, “it ends up being chaotic and cluttered,” Sumner said. Conversely, people without the disorder “might look at objects in their home and have this implicit, intrinsic subconscious ability to know where objects go, to know what is not important and what they can get rid of,” she told Braindecoder. “So they don’t have that clutter.”

In fact, previous research has suggested that people with the disorder tend to be under-inclusive in how they categorize the things they have, Sumner said.

“If you give them 10 objects to sort, they may put them in 10 different categories because they are all unique and complex in their own way,” Sumner said. But if a person without the disorder is given the same 10 objects, they may be able to put them in just two different groups, so they are easily organized and there is no clutter, she said.

“So we have this ability implicitly to decide where things should go,” which many people with hoarding disorder may not have, Sumner said.