I happen to agree with these figures. The figures involve the intelligibility of various Romance languages, spoken and written, for speakers of Spanish.
Intelligibility for Spanish speakers, oral: 77% of Galician, 55% of Catalan, 54% of Portuguese, 25% of Italian, 1-5% of French and many Italian dialects.
Written: 93% of Galician, 90% of Catalan, 85% of Portuguese, 50% of Italian, 16% of French.
As you can see, the figures are much higher for written than spoken language. This makes a lot of sense. With my fluent Spanish and some knowledge of Portuguese, French and Italian, I can pick up a fair amount of the written text of any Romance language.
Orally though, I’m typically pretty lost. The best ones are those that are closest to Spanish, such as Andalucian dialect, Aragonese, Asturian and Galician. Leonese is a lot different, heading towards Portuguese. You get to Catalan and Occitan and I start having lots of problems. Portuguese is way harder than you might think, even with my rudimentary Portuguese. Standard Italian as spoken slowly by say a documentary narrator is a bit better. Street Italian is nearly useless to me, as is Spoken French, Romansch, Romanian, Italian dialects and hard Andalucian.
It’s very interesting that Spanish speakers can understand Galician better than they can Portuguese, but it makes sense. After all, Galicia split off from Portugal long ago and came under the influence of Castillian. I am not sure which Galician they are referring to here. There is a soft Galician that is used on Galician TV which has very heavy Castillian influence. Even I can pick it up pretty well. But there is a hard Galician of the street and the rural areas that is much harder to understand.
The figure for Catalan is much lower than for Galician because Catalan has so much French influence. Look at the dismal figure for spoken French and you can see why Spanish speakers have a hard time with it.
25% intelligibility of Italian sounds about right to me. Spanish speakers can understand Italian much worse than they can understand Portuguese. The figure for French is shockingly low, but it makes sense, as previous studies have shown that nobody can understand the French.
I would agree that Standard Italian, especially spoken slowly by a professional speaker, is much easier to understand than many Italian dialects, which are actually spoken languages. I’ve seen them on Youtube and I can’t make out a single word.
With my Spanish, my figures for written intelligibility of Romance are not as high as those above, but I’m not really fluent as far as reading Spanish goes. I’m a lot better at speaking it and hearing it. Others have given much lower figures than the one above for Spanish speakers reading Galician, but it probably improves very quickly in a short period of time.