The Psychological Record

, Volume 67, Issue 1, pp 81–96 | Cite as

The Relation Between Sorting Tests and Matching-to-Sample Tests in the Formation of Equivalence Classes

  • Erik Arntzen
  • Sjur Granmo
  • Lanny Fields
Original Article


Using the simultaneous protocol, 20 college students attempted forming three 5-member equivalence classes (A → B → C → D → E). In Group 1, baseline training was followed serially with a sorting test, a matching-to-sample (MTS) test of derived relations, and a second sorting test. In Group 2, baseline training was followed with an MTS test, a sorting test, and a second MTS test. In Group 1, initial sorting showed the immediate emergence of three classes for five, one, or two classes for three, and no classes for two participants, respectively. The MTS test documented equivalence classes for three of the first five, one of the next three, and none for last two participants, respectively. Across participants, 19 of 27 classes in sorting (70 %) predicted presence/absence of corresponding equivalence classes in MTS tests. For three participants in Group 2, initial MTS testing showed immediate emergence of all equivalence classes with their maintenance in follow-up sorting tests. Three others showed no classes in MTS testing and emergence of all during sorting, documenting delayed emergence of classes. The last MTS test documented equivalence for one of these three participants. Two others showed no class formation in any test. With five of 16 participants who showed class formation in sorting, the positioning of the stimuli in sorting reflected the nodal structure of the classes. Variables that should increase prediction of equivalence classes by sorting were discussed.


Sorting Stimulus classes Stimulus equivalence Immediate emergence Nodal structure College students 


Compliance with Ethical Standards


This research was funded by Oslo and Akershus University College.

Conflict of Interest

The Authors declare that there is no conflict of interest.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Association for Behavior Analysis International 2016

Authors and Affiliations

  1. 1.Department for Behavioral ScienceOslo and Akershus University CollegeOsloNorway
  2. 2.Queens College and The Graduate SchoolCity University of New YorkNew YorkUSA

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