Objects are crucial in our account of relations just as they are in all accounts. For our purposes, object instances are cognitive entities (rather than entities in the external world) consisting of values on dimensions such as color, size, extent, material. Object categories such as BOWL take the form of ranges of values on each dimension. They are developed from repeated experiences with individual instances.
Playpen's representation of objects is illustrated in Figure 14. Each rectangle represents the pattern of activation on a single object dimension (e.g, vertical extent, horizontal extent, color). The particular values on these dimensions presented by this single object instance are indicated by the blackened region. Thus, Figure 14a might represent a particular object that is 8 inches tall, 20 inches long, and blue. The presented values on the three illustrated dimensions are associated by the illustrated connections among them. Figure 14b illustrates an object category which consists of a range of values (features) on the different dimensions defined by the correlations among features found over multiple instances. Thus, object-feature correlations begin with the inter-value connections that are created (or strengthened) with the presentation of an object instance.