1. Chapter 3 Spatial Interaction and Spatial Behavior The Movement of people, ideas, and commodities within and between areas

2. Questions Factors influence human’s decision on interacting with space How does distance affect the decisions Space activities and exchange of commodities Migration decisions

3. Bases for Interaction Unevenly distributed resources in the world – make commodities flow Summarizing Model – proposed by Edward Ullman: 3 factors controlling the space interactions: –Complementarity –Transferability –Intervening opportunities

4. Complementarity Supply of items in one place and effective demand from the other with purchasing power Effective supply and demand are important considerations – fig 3.2 and exchange of raw materials and industrial commodities between less developed and developed countries.

5. Transferability Consideration of time and cost, once the complementarity exists. An expression of the mobility of a commodity and a function of three interrelated conditions a) characteristics and values of the products b) the distance, measured in time and money and c) the ability of the commodity to bear the cost of movement. Mobility is not just a physical but an economic matter. Transferability is not a constant condition. Highway, seaway opening, transportation means change.

6. Intervening Opportunity Reduce supply/demand interaction that otherwise might develop between distant complementary areas. Jobs available in midway between home and destination. Opportunities closer at hand reduces the pull of opportunities offered by a distant destination (fig 3.3)

7. Measuring Interaction Distance Decay- the decline of an activity or function with increasing distance from its point of origin Inverse square relationship Friction of distance is reduced by lowered cost or increased ease of flow. Cellular phones usage, expressway extend commuting travel Gravity Model – the expected interaction (I) between two places A and B can be expressed as: I = (P a * P b )/D ab and Exchange between these two places I ab = (P a *P b )/(D ab ) 2 and the breaking point (BP) is BP = D ab / [1 + sqrt(P a / P b )] (fig 3.5)

8. Interaction Potential More than 2 places interact in real world. The more specialized the goods produced in each separate center, the greater their collective complemetarity and the more likely is it that such multiple interactions will occur. Summarize the size and distance relationship between all points of potential interaction within an area. Movement Bias – direction bias (fig 3.6)certain places have a greater attraction than do others. East-West flow bias in N America.