Spatial Span Task

Spatial span task - visuospatial working memory capacity

The spatial span task measures visuospatial working memory — the ability to briefly hold and manipulate the locations of stimuli in space. It is the spatial counterpart of the verbal Digit Span Task and is most often implemented as the Corsi block-tapping task.

The Spatial Span Procedure

A set of identical squares (or cubes) is shown. On each trial, a sequence of locations lights up one at a time. The participant must reproduce the sequence — either by tapping the locations in the same order (forward span) or in reverse (backward span). The sequence length starts short (e.g., 2 items) and increases until the participant fails several trials at a given length.

The standard measure is the spatial span — the longest sequence reproduced correctly, often reported as the maximum length or as a span score derived from the number of correct trials.

What Spatial Span Measures

Spatial span indexes the capacity of visuospatial working memory, thought to rely on the posterior parietal cortex and linked to the "visuospatial sketchpad" component of Baddeley's working-memory model. It separates two things:

Storage capacity — how many locations can be held.
Manipulation — backward span requires reordering, engaging central executive control more than forward span.

It is sensitive to aging, neurological injury, and individual differences in spatial ability, and correlates moderately with fluid intelligence and with other executive tasks like the Tower of London.

Relationship to Other Tasks

The Corsi Block Tapping Task and Backward Corsi Task are the canonical implementations.
The N-Back Task also loads visuospatial working memory but with continuous updating rather than serial reproduction.
The verbal Digit Span Task measures the analogous phonological capacity.

Why It Matters

Spatial span is a compact, reliable index of a core memory system. It is used in clinical assessment (e.g., for visuospatial deficits), in research on memory capacity limits, and as a dependent measure in studies of training and aging.

Methodology

Methodology: This topic is part of the experimental workflow covered in Experimentology. For the relevant methods, see Measurement (span scores and their reliability; forward vs. backward as distinct metrics), Design (adaptive length as an independent variable; forward/backward as a factor), and Sampling (trials-per-length trade-offs).

Corsi Block Tapping Task - The canonical implementation
Backward Corsi Task - Reversed-order reproduction
Digit Span Task - Verbal working-memory analog
N-Back Task - Continuous updating of working memory
Tower of London - Planning that uses spatial working memory

Implementation

A jsPsych implementation of the spatial span task is part of the ExpFactory experiments collection, which provides browser-ready working-memory paradigms.

References

Corsi, P. M. (1972). Human Memory and the Medial Temporal Region of the Brain (Doctoral dissertation, McGill University).