a portable computer

In research articles from the 90's, the authors usually get specific about their equipment:

"Two tasks were administered, a timed grammaticality judgment (GJ) task and a question formation (QF) task. The GJ task was administered on a portable computer (Macintosh Powerbook.)"

Either this is some secret product placement scheme, or the researchers actually think their choice of computer makes a difference. Who knows? Maybe tomorrow some exposé will come out discounting all studies done on IBM ThinkPads (they've been skewing the data for years in favor of big business.) Fortunately, these authors will be safe because they used a Powerbook! OR VICE-VERSA.