Activity (Alternative) 13.6 Haptic Object Recognition

Klatzky, Lederman, and Metzger (1985) performed a study in which 20 college students were asked to identify 100 common objects by touch alone. Participants were seated at a table with a blindfold over their eyes and headphones (playing white noise, to mask any sounds the objects might make) over their ears. One object at a time was then placed on the table in front of them and then the experimenter tapped their hand to let them know that a trial had started. Subjects picked up the object and attempted to name it (objects were selected so as to be easily to hold).

The results were pretty remarkable: Of the 2,000 naming responses given in the study, 95.8% were correct—and many errors were trials in which the subject provided a name that was too broad to be counted as strictly correct (e.g., saying “vegetable” in response to “pumpkin”). Furthermore, participants were also quite quick: 94% of responses were given within five seconds of the participant’s first contact with the object.

If you can recruit a friend to help, this activity will let you try this procedure yourself. Ten of the objects used by Klatzky et al. are shown at left. (The objects are: teacup, envelope, eyeglasses, key, lightbulb, pencil, screw, screwdriver, sock, and spoon.) Collect as many of these objects as you can, give them to your friend, and blindfold yourself (alternatively, you can shut your eyes, as long as you do not peek).

On each trial of the experiment, have your friend choose one of the objects at random and click on its picture at left. He or she should then place the object in front of you, tell you it is there, and watch as you try to identify it.

In addition to testing your recognition accuracy (which will probably be close to, if not fully, 100%), we will also use this activity to explore the notion of exploratory procedures. Six such procedures, each one a particular way of feeling an object in order to extract one or more of its properties, were identified by Lederman and Klatzky (1987) as being commonly used by people as they attempt to haptically identify and manipulate objects.

Once you are set up, you and your friend should review the trial instructions, so that you are both clear about exactly what you both should be doing on each trial. Then have your friend start providing you with objects.

After you have completed all 10 trials (or as many as you could collect objects for), click the “Trial Results” link at left to view your results.

Trial Instructions
Have your friend watch you as you attempt to identify the object that he or she has just given you. If you perform any of the actions listed below during the identification attempt, your friend should click the action’s picture or checkbox:

  • Lateral motion: Subject rubs hand or fingertips across the surface of the object.

  • Pressure: Subject taps or presses down on the surface of the object.

  • Static contact: Subject holds hand or fingertips in static contact with the object.

  • Unsupported holding: Subject hefts the object in hand, unsupported by any other surface.

  • Enclosure: Subject places one or both hands around the outside of the object.

  • Contour following: Subject uses one or more fingers to trace the edge (contour) of the object.

Once you have produced a name for the object, your friend should click one of the buttons (“Correctly” and “Incorrectly”) at the bottom of the screen at left to indicate whether or not you correctly identified the object.

If you understand the instructions, click on a picture above left to start a trial.

Trial Results
As noted in the introduction, the 20 subjects in Klatzky, Lederman, and Metzger’s experiment named about 95% of the objects correctly, on average. You have correctly named some proportion of the objects you have tried, as shown in the table at left.

Think about the exploratory procedures you used while identifying the objects, summarized in the table at left. Lederman and Klatzky found that people used each procedure to examine a different property of objects:

  • Lateral motion: Texture

  • Pressure: Hardness

  • Static contact: Temperature

  • Unsupported holding: Weight

  • Enclosure: Global shape, volume

  • Contour following: Global shape, exact shape

Did you use these exploratory procedures in the way that Lederman and Klatzky outlined? Which exploratory procedures did you find most useful for this haptic identification task?